Commercial airlines are encouraged by national governments to provide abysmal service and conditions, as are airports encouraged to make everything as squalid and unpleasant as possible. This is part of a Deep State plan to encourage people to become more entrepreneurial and thus boost the economy. If we all start companies and they are all wildly successful (because, as per Lake Woebegon, everyone can be better than average, right?) then we can all afford to fly GA and thus be spared the unremitting horror of commercial air travel. Even a small private jet is infinitely better than Business/First in a US carrier.

If this isn't the reason things are so bad, then the only remaining reason must be that... everyone buys the cheapest ticket they can find, thus sending a clear message to the airlines that regardless of how much people complain, it's only price that really matters. And the cheaper the ticket, the worse the experience.