Solarpunk technology

Airlines are too fast in several senses. First, people don't usually need to get somewhere as quickly as an airline allows. Someone who is really on urgent business can use telepresence or a charter instead. Second, the airports on either end of a trip are frequently too slow, making airlines and example of "hurry up and wait". Third, airlines move people through timezones very quickly, exacerbating jet lag.

I agree with you that airlines are too uncomfortable even for their speed to overcome. Slow travel can be much more comfortable. For example, many people are willing to spend days on trains and cruise ships.