Really anything based on a belief that youth are incapable of thinking rationally

Incapable? No.

However, it's well known that teen brains are still developing -- especially the part able to discern consequences to actions:

Jensen says scientists used to think human brain development was pretty complete by age 10. Or as she puts it, that "a teenage brain is just an adult brain with fewer miles on it."

But it's not. To begin with, she says, a crucial part of the brain — the frontal lobes — are not fully connected. Really.

"It's the part of the brain that says: 'Is this a good idea? What is the consequence of this action?' " Jensen says. "It's not that they don't have a frontal lobe. And they can use it. But they're going to access it more slowly."

The problem with your idea (aside from "where is the money going to come from") is that, judging from your lack of acknowledgement of kids/teens needing good guiding adult figures in their life, they're not going to make the best decisions by themselves. That's not to say anything about not wanting to remove the children from abusive homes. Rather, I mean that kids/teens can learn the basics of how to take care of themselves because it's not hard -- buying basic groceries and such.

However, who is going to guide these children outside of school? Who is going to spend the time to try and make sure these kids grow up to be as well adjusted as they can be? Letting kids raise themselves with only a series of "tests" to check on development is leaving a huge oversight gap. The argument that "some kids could do it successfully" is not compelling enough to let all kids do it.

I like the idea of helping young folks get out of abusive situations, but your solution is full of thought gaps.