the whole thing was framed as a master-student affair

Some of it was that, but much of it was simply prostitution. The children of the poor who couldn't support or educate them ended up in the streets surviving however they could, and that often meant finding their way into prostitution, especially if they were physically attractive. I saw a news report talking about how it's going on now with Syrian refugees in places like Greece and Italy. They hang out in parks at night, and men come, pick them up, and pay them for sex. They don't identify as gay, but they have no other way to feed themselves.

That's part of why I think the New Age romanticizers are so off-the-mark. I think it more likely that these early societies were more like what's described in Game of Thrones than they were like some fantasy of sexual/gender utopia prior to contact with Western Civilization. The less powerful have always been subject to exploitation.