@Anthony ********
, If I understand right, same requirements to enter Thailand (at the immigration on entry point, air, land, or sea) for tourists, for both visa-exempt or tourist visa entries. When you have SETV, you still might be asked for three proofs (funds, accommodation, onward travel), and you would be refused to enter Thailand if you cannot show.
It's more airlines' policy that they check your outbound ticket only when you are without a visa.