Who’s they?

When our clothes and electronics or whatever mostly or exclusively come from the other side of the world, I don’t think it’s because corporations are taking advantage of economies of scale so much as they are doing arbitrage for labor and environmental protections. If we bring production closer to the people who need the products, then we get jobs, autonomy, and accountability. We can still have economies of scale at the regional level. Not every town needs the same set of factories of course.

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.

Because I think it’s bad economics to try to transport finished goods over long distances quickly. It’s better to transport raw materials long distances slowly (ship and rail) and employ people to manufacture things near where they are needed.

Yes, but for passenger service rather than cargo. Passenger jets are too fast, too uncomfortable, and cause too much pollution.