There’s also the reverse problem in Thai with Beach Boys, and not former members of the band. Young Japanese women go over to Thailand on vacation and meet young local men (traditionally on the beach, hence the name). The women will wind up supporting these guys. I’ve seen a couple of TV programs where they talk to these girls.
Most of them are pretty normal, and some are pretty aware of the game, but still are going along, “for now” as one woman said.
Yes, there are quite a few female sex tourists, too, but you never hear about them. They’re not newsworthy.
Unless you are Japanese, at which point they become a curiosity, especially to the Japanese producers. “Why would a Japanese woman not prefer a nice Japanese boy?”
The other reason, I’ll guess, is that women would typically not go for underage people, unlike many other sex tourists.
True. And it’s not always the guys they go for either. 
But in fairness to the farang men, they tend not to go for underage either. Those guys head for Cambodia.