That's not actually true. Unbeknown to me, a CM immigration person failed to stamp the new visa date in my passport. When I got to BKK, all hell broke loose and I was shouted at and threatened. There was a distinct absence of a Thai smile. And I had the CM receipt etc. I got fined and an overstay stamped in my pp. On another occasion I went to Hong Kong. When I got into CM, I was told to get on a plane back to HK. The assumption was that I was working as I had so many stamps in my pp. I was not. They made it clear that I had to pay a bribe. There were 5 of them. And this has happened to many, many people. (The bribe they like is about 2000 I believe. I didn't know that as I've never had to pay a bribe in my life and so ended up paying 4.
'From 1 October 2022 to 31 March 2023, British passport holders arriving by air or land can enter Thailand for 45days without a visa (a ‘visa exemption’).'
Much depends on the immigration officer. I did this many, many times and it was fine. However, on my return from a visa run to HK I had a terrible time in CM. I was shouted at, accused of working - I was not working - and told to get on a plane back to HK. That then seemed to change and then money had to be paid. It was a horrible experience and to be faced with 5 people shouting at me the day after a relative had died made it all the worse.