They want to encourage the wealthy elites with private planes or charter flights. A very small group but they get more bang for the buck and the groups will be small enough to monitor and control.
You don't even legally need a passport for a domestic flight, just legal photo ID, but with the Covid situation AOT is trying to track all foreigners and on my last flight from Hat Yai to BKK and back I was asked for my Passport four times.
Under "Normal" circumstances (pre-covid) you could just arrive on a 30 day exemption then get a 7 day extension. You can also apply for a 30 day extension if here legally. Now, however, I would suggest getting a Tourist visa, which you can apply for by mail. (see link)
Try Vietnam. They had a handle on things, some recent problems but they acted quickly. Good bet Thailand will establish travel arrangements with them soon.