And then there's dark pools. Trading isn't even done on the market anymore.
This is such a non-sequitor, it undermines your entire post.
Food: - restaurants definitely compete with each other, mostly in each local area - and within that, different slices of the restaurant business more directly compete, e.g. fast food is more competing with each other than fine dining. - BUT: we have a huge problem with a lack of competition in the supply chain driving prices up for everyone, at least in the US. - Groceries are similarly impacted by supply chain monopolies
Smartphones: high end smartphones are a oligopoly: - Apple vs Samsung vs HTC and several other tech companies producing phones; Apple definitely commands quite a bit of a premium, as do some of the nicer Android phones. But on the whole, the companies really are fighting to one-up each other with better features, battery life, etc. - quality is improving, even if the price is over-charging vs the ideal competitive market. Low end phones are even more fiercely competitive
Other electronic categories seem to show decent market dynamics; headphones, earbuds, usb peripherals, keyboards, etc. all seem very commoditized; there certainly are brands that try to command a bit of a premium based on reputation / marketing, but the cheap options are often good enough and definitely have a very competitive market. Big electronics like GPUs and gaming consoles though I think it's easier to start considering market distortions due to more monopoly power.
Of course there are no shortage of monopolistic practices out there, e.g. for utilities, collusion on rent, online retail (Amazon), textbook prices, medical care & pharmaceuticals, and even more mundane things like frozen potatoes and chicken.
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The thing that bothers me most with the simplistic view that "the market will do it better" is that the whole premise of market forces giving the most efficient price assumes that (a) a commodity is being traded by (b) a large number of buyers and sellers, none of whom have any significant share of the market. Many markets either (a) aren't trading a commodity (e.g. iPhones and Android phones aren't interchangeable so Apple can command a premium price) or (b) have consolidated buying or selling to the point that they don't have the large number of independent buyers or sellers necessary to have the price be set by market dynamics rather than the monopolist or monopsonist. And the people promoting "let the market fix it" either are too dumb to realize that, or more likely are letting their rich friends make a quick buck or want to score political points by promoting smaller government.
What could be interesting is to have the local government found a co-op, i.e. they issue a bond to do the build-out and then hand the network to a co-op in exchange for a contract to pay the debt, essentially giving the co-op the backing of the government's credit rating for the initial build-out. Then the co-op board gets separately elected by its customers so they're directly accountable to the customers for any shenanigans.
All that to say, voters here do care about utilities, and the coop solution worked for about 25 years iirc but it can't work in today's "one solution fits all" regulatory context anymore, at least where i live. Things are far from that simple in practice.
For trains it's much harder - yes, there are two providers on the WCML, but they're not equal (one runs faster trains) and as such there's zero real competition.
So you have the government own the tracks, contract with a private company to maintain them. Then anyone can use the tracks, like anyone can use the roads. Private companies offer train service to the public. All they need is rolling stock and they can start selling tickets. You then get a market that looks like airlines, i.e. entering the market is a moderate investment (millions; buy rolling stock/planes) rather than needing billions to build the network itself. More popular routes get more suppliers, which turns into more frequent service. There is plenty of competition because rolling stock is mobile and can easily be reassigned according to customer demand.
That said, who is to say the trend isn't reversible some day.
Also let's not forget the selling to private operators does provide benefits, not always, it's not the magic fix we pretend it is.
To see some examples of this, look at the arguably social democratic Keynesian US from the fifties, and where they're at now. Similarly for the United Kingdom. Labour used to fight for social democratic policies, and since the advent of "New Labour" (Thatcher's greatest victory), they're essentially a right wing party. For a much more harrowing example, look at Allende in Chile and the US sponsored coup by Pinochet.
In general what you see is that the social democratic status of a state is an unstable one. Roughly speaking, the people who would benefit from neoliberal policies happen to have a lot of money with which they can and do influence politics. There's campaign funds, lobbying, but much more importantly owning the media[1]. Propaganda is incredibly powerful (we are not immune), and it has been used successfully time and again to get people to vote against their own interests, such as abolishing social democratic practices.
[1] In the case of Chile, and for example Indonesia, the mechanism is much more violent, but the principle the same. Capital is spent to successfully influence politics in favor of capital.
The best system is a free market, if possible. But the second best system may not be close to the best system, it may be a local minima that is very different.
A classic example is that small companies and no unions is theoretically best, but monopoly unions vs monopoly companies is the second best (since there's no single monopoly, so they negotiate something close to the theoretical ideal).
Free markets are best, but if the government is going to heavily subsidise and regulate the power companies (as they are natural monoplolies, so they either get regulated or they abuse their position) then maybe it's best to just cut out the middle man.
This premise is highly questionable. Certainly for competitive markets it's entirely false. Uncompetitive markets suffer largely the same failure mode as government bureaucracies, but it's not even clear that this is actually worse, because government bureaucracies are susceptible to not only charging bloated service fees for mediocre service, they can also be captured into diverting tax dollars to private cronies. Just because the government owns the real estate doesn't mean it's manufacturing its own trucks and networking equipment and copy machines, but as soon as it isn't, it's buying that stuff from the market and you need a competitive market or you're still screwed.
So what it comes down to is, you need a competitive market.
Apologists love to complain that <insert problematic market outcome> isn't the product of a true market but that dog doesn't hunt. We have the economic system we have. We call it capitalism. It produces the above mentioned (and countless other) excerable outcomes. No excuses.
It seems there are at least two, such as in the case of utilities: best services or best profits for the shareholders. Again in the case of utilities we see time and again that these are mutually exclusive optimums as a privatized utility makes cuts to investment, build out, maintenance, customer service, or other aspects of the business in the goals of increasing profits, to the detriment of the quality of their service.
This is a pretty bad example because monopoly unions vs. monopoly companies is extraordinarily bad to the point of being a plausible worst case scenario. The company is then free to run roughshod over its customers and suppliers and use its resources to capture the government and the union not only does nothing to prevent this but actually encourages it because then they can extract more of the monopoly rents for themselves. Then the normal tendency for the public to demand antitrust enforcement when met with an abusive monopolist is blunted by the union's support for the monopoly and prevents the monopoly from being toppled.
