@Leo ********
Many countries do fine airlines for bringing passengers who don't have the right entry documentation. But that is in country's which check such things like the UK, USA etc.
Thailand immigration never does but I guess in theory they could check. But then if you showed the airline a fake onward ticket surely they would be fined anyway, so why don't they check??
Plus not all airlines to Thailand do this. I've flown to Thailand many times. Only Qatar have this policy, and in SE Asia only Air Asia and Vietnam Airlines have asked.