by the looks of your comments on this thread you’re only posting here to clap back at people and start a fight. Several people have told you you don’t need a return flight. Your experience with a particular airline was due to THEIR POLICIES, not Thailand’s immigration process. I won’t be replying again.
he’s not joking, that’s exactly how it works. I’ve travelled to Thailand many times, both with a return flight booked, and with open ended travel plans (no onward journey / accomm booked).