I'm not sure about that alternative. Once I ran out of science classes to take in-house my public school just sent me to college early and paid for the classes. This was 2004, not sure if that's a thing anymore.
The scam is that there's nothing at the end of the road. You get these students that are borderline suicidal because they absolutely must outperform their peers, but it's all just ladder climbing and performance for performance's sake. That takes a toll on a person. And for what? Nobody under that kind of pressure is capable of learning anything.
Then they get to college or industry and they have to work with their peers, or apply creativity in some way, but they can't do either of these things because they're either burned out or preoccupied with scoring points in a game that nobody else in the room is playing--or at least that has been my experience with the people who made me aware that they went to private school: too focused on value to be useful in achieving outcomes. Incapable of making the best of a situation that they feel they're too good for.
Admittedly, there may be people around me who came from that background and I just don't know. It's not like I question people on it. But if that's a blindness I have it's not one I can introspect my way out of. You don't know what you don't know. All I have is these anecdotes about folks who are a sort of walking ad for whatever prestigious rigmarole they managed to survive. Eager to establish some kind of pecking order wherever they go and not invited places because of it despite being otherwise pretty cool.
I don't know if charter schools do the same thing to people, but they appear to be trying--and they've found a way to make the rest of us pay for it despite it being exactly the opposite of the what we're ostensibly paying those taxes for.
Does it really not feel like a scam to you?