Someone underage (18 by international UN Convention ratified by around 200 countries) cannot legally sell sex, and since they cannot... it is by default non-consensual - which means trafficking is applicable. [same logic behind statutory rape - no defence of it 'was consensual']. Widely publicized nabbing of them, makes it more difficult to let it slide for money... even if it was possible - most western countries laws on this subject extend to their citizens travelling in other countries. I can pretty much guarantee that someone from each of those embassies are in contact with Thai police requesting to be kept abreast of all the legal evidence as well.