The reason is monetary policy. The Fed constantly 'prints' new money out of thin air and injects it into the economy via a combination of 1. loans to the government and 2. open market operations. Guess who gets the first dips into these two huge pots of newly created money?
In the case of government money (loaned by the Fed), big corporations get a huge chunk of that money pot because they get all the lucrative government contracts. In the case of open market operations; big finance firms like Goldman Sachs and big traders with insider information are the first to get their hands into that pot.
Basically that money which is meant to 'trickle down' isn't actually doing that; instead it appears to be trickling back up to government officials who are enacting policies that benefit corporations and increased centralization of wealth.
The Fed mostly buys government bonds, the markets for which are very liquid and efficient.
(The government however does benefit from the Feds buying their bonds, instead of injecting money into the system some other way.)
There is a significant delay before the newly created money affects wages. Shareholders benefit from the new money instantly (since the market reacts to it quickly and it drives up the value of their stocks) but wage earners won't benefit from the new money until they get their annual 2% salary raise at the end of the year. That delay is significant because it allows shareholders to compound their ROIs several times before wages catch up.
On the one hand, no one has yet figured out how eliminate inefficiences out of large organizations. They're all like that, usually the bigger the more inefficient (the government, because of its size, being obviously the worst offender).
However, it seems that it just takes dozens (if not hundreds) of thousands of employees to run say a top tier car or microprocessor company. You just can't do it with less, so the inefficiencies are the cost of producing such advanced stuff as say BMWs or Intel processors.
