3. they arrive in and depart Thailand by any means of transport (air, land or sea) through immigration checkpoints, any confirmed tickets to leave Thailand within 30 days from the arrival date at the port of entry in Thailand must be obtained.
copied again the last part of the rule !
and again the rule not says that one has to go out of the country on the same ticket ! You just have to leave Thailand after 30 days in any way.
From Phuket we do this with so called VISA runs. They every day start in Patong by minibus to the boarder of Burma. ow. 4h. trip, so return same day aftenoon. costs around 1200 THB 20 GBP and one has the next 30 days entry. This one can do every month. Or like my friend, he has some reservations for LCC Air Asia out of Thailand after every 30 days. But itīs absolutely not BAīs concern that he leaves Thailand after 30 days on a BA document. They only have to proof the vality of his passport, and that he holds a valid return ticket ! ( which he had, and he could easyly rebook it if nessecary there, if he needs, because the rule allows changes at any time ! )