I think the other factor is a bit of anchoring. I know this impacts me anyways. If there is a "free" alternative, then that's where I'm anchored at. I can watch youtube for free so paying for it seems like a bad deal. Where as there is no free alternative to Coke that still gets your Coke (as opposed to say water).
Flight comparators don't show "avaliable legroom" in their metrics.
As far as I know some companies charge more for seats near entrances where there's more space, so people are willing to pay more.
In my anecdotal experience, the people complaining about leg room are precisely those who are not paying for additional leg room. (Similar to how people who compare modern air travel with service in the 1960s aren't purchasing the inflation-adjusted equivalent ticket, which would almost always be a lay-flat seat today if not Wheels Up.)
Unfortunately those prices are usually not even close to proportional to the additional space (and even that would ignore that seating space is only part of the service).
This is true. One thing I note is that with the same dollar amount, you get even less legroom, luggage, etc. today than you used to back 10-15 years ago on traditional airlines. Granted the airline costs rose over time, but it's hard to imagine they went up to the scale traditional airfare has increased at equivalent service levels... Also the fact that things that used to be included are now considered "extra" looks like a good excuse for folks to complain about.
Even then the second most profitable line of business for airlines are credit cards and the banks who buy miles in bulk for their customers. Of course this is a US perspective.
How to you qualify the comfort of a seat with 20cm of legroom vs 30cm? Until we have a quality metric for flights that's also a single number we can't.
Strangely, some of my colleagues have 'paid' (work's money, their time) extra to avoid Ryanair, when Ryanair has the only direct connection. This I find strange.
Given the choice, I've long paid a little more if it means an Airbus plane, as I think the cabin is quieter. However, that's rarely shown on flight booking sites.
