If I understand correctly, anyone who fails a covid test in Thailand is still sent to some kind of hospital, whether they need treatment or not.

So if I have any say in the matter, the only swab I intend to have in Thailand will be whatever is mandatory on arrival.
I'd imagine locals, expats and other tourists will mostly avoid tests for the same reason.

If I have symptoms, I'll test myself with a lateral flow test.

As for vaccines, that's interesting. I might leave the UK before being eligible for my booster jab, so if any private hospital or vaccination centre is offering mRNA jabs without needing proof of residence, I may be a customer.