In some ways, yes, I think it is a good thing. Channeling people into vocations at 18 [US system] or 10-13 [German system] isn't consistent with what is known about human development in general, and brain development in particular [http://hrweb.mit.edu/worklife/youngadult/changes.html] - and that's the scientific part of your question. The human cost of such channeling may be seen even here on HN [http://news.ycombinator.com/item?id=2238225] where fortunately for the poster he has access to the US educational system.
Who should pay for what is a political question - but in general the US system is pay to play and most students are not subsidized by with public funds (even though their loans may be Federally guaranteed).
> Channeling people into vocations at 18 [US system]
> or 10-13 [German system]
Don't exaggerate. Yes, it's true that there's some segregation going on at that point (Gymnasium versus Hauptschule versus Realschule), but the boundaries are permeable.
Even if one assumes that students stick to their "path," that doesn't mean that they don't have a choice over their vocations later on. You're free to do whatever you want. Most students start their first degree when they're 21/22. 30-35% (IIRC) change "major."
I wouldn't say that HE flexibility is a specifically American strength.
Who should pay for what is a political question - but in general the US system is pay to play and most students are not subsidized by with public funds (even though their loans may be Federally guaranteed).