My experience from 1998 to 2023, and tens of dozens of times both leaving and entering on visa exempt. I only once got Red stamped. Was still let in for thirty days, but then got a 12 month multiple entry 'O' non-immigrant, so as people say it all depends on the IO on the day. In those twenty five years I only ever got three two month tourist visas and the one 12 month visa. In fact I was leaving and re entering that much that in one period of ten years I had to renew my passport five times because of all the stamps both Thai and from other countries. My passports were all 48 page ones as well.