It's probably important to be specific when I say "quality." By that I'm referring to ease of purchase, fair baggage prices, web/app UX, on/off-flight customer service including pilot communication with passengers, and even landings (as a pilot, I am absolutely judging beyond "did we get to the ground safely or not"). Price and seating are secondary for me, although I certainly understand why they are list-toppers for others.
I suspect flying up front on any of the majors is fine. Economy experience is driven by a race to the bottom price-wise, but if you want cheap travel, it’s readily available. If you want comfortable travel, that’s also on offer.
I flew Frontier the first time this Spring - was helping ferry an open cockpit biplane from Colorado to Illinois - and it was a stupid cheap one way fair. I really can't think of a single perk Frontier did not try and up charge a fee for. Boarding, luggage, carry on, seat assignment... I'm sure there were others. Funny enough, the guy I was ferrying with also picked the cheapest seats in the plane, so we ended up next to each other on the flight out. I was fully prepared too wear the kevlar helmet on the flight rather than pay the $60 carry on fee.
What's so awful about United?
My point was that even though the regular flights are similarly priced in the US and Asia, the quality in the US is so much worse. I now see that my attempt at explaining this discrepancy had some flaws, but what other explanations do you suggest?
The fact seems to be that even the best US Airlines are significantly worse than the ones in other places. When the best rated ones are hovering around average, there is something wrong.