They DID choose these people

If you read the article, you'll see that they willingly took up with these people, who were not blood-related to them and who treated them well at first, but the abuse was a gradual thing and by the time they were fully immersed in it they were under this guy's spell and afraid of defying him. See, that's a double-edged sword for us because, pertaining to people they are living with, kids are much more likely to be abused by adults not related to them than those who are related to them. This is because true parents have a genetic investment in their own offspring. Obviously it's not foolproof, but have you noticed that whenever you read about a child being brutally murdered at home, it is almost always a stepparent who is the culprit? The same is true of incest and incestuous abuse cases, by the way:

"For stepfathers and stepbrothers, there is no genetic cost at all. It is no surprise, then, that between half and three-quarters of all reported incest cases are between stepfathers and stepdaughters, most of them initiated by the stepfather." (Stephen Pinker, How the Mind Works, pg. 458)

Moreover, as Pinker goes on to say, blood relatives who do commit incest almost never grow up together (thus muting or overcoming the Westermarck Effect.)

That said, I agree that kids' situation needs to be more fluid, but given what we know about stepparents/caretakers vs. real parents, this could potentially make a situation worse for kids, so there has to be more to it than just kids being able to choose whom they live with. Kids need stability too, and we don't want them bouncing around from one abusive prick to the next or winding up on the streets. We need to be able to verify that the situation is okay for kids. I propose a tradeoff here: society allows kids more freedom in general, but with kids who opt to go out of their parental homes, the state has to look in on those kids as a matter of course every so often. Of course, that would only apply to children who had not yet emancipated themselves via the Epstein mechanisms. Giving kids freedom to go where they choose can solve some problems, but it could also be a huge pain in the ass and make the situation much worse for kids, as often happens with kids who run away from home.