i don't actually know the answer, but here's a guess. imagine you are going on a trip and you are planning your outbound flight and first night's accommodations. you suspect that the price will go down at the last minute so you put off making reservations as long as possible. which are you more willing to risk, having a place to sleep when you get there, or getting there on the day that you planned? i suspect most people are more comfortable risking a late arrival than arriving with no place to stay.

Also, people go through some pretty extreme lengths to cut costs on the traveling (airfare) part of a trip compared to the accommodations (hotel) part.

For a plane ride, people are willing to put up with zero leg room, multiple hour layovers, red eyes, zero free bags, etc. just to save a few bucks. I think it's because the plane ride is seen as a means to an end, rather than part of the actual vacation or trip, so suffering for a few hours is palatable to most people.

Some airlines do this.. like Wow.. or Ryanair. They usually start the other way with cheap first then really expensive but sometimes you can find them still at the cheap level.