> Caltech can afford to treat their students like adults, because they're picked from the cream of the crop.

The cream in terms of demonstrated capacity for academic performance, which probably has very little correlation to readiness to be treated as an adult. There selection criteria is why they can afford to have rigorous coursework as the basic freshman core, but not why their decision to treat the young adults attending as adults works.

If anything, that policy is part of the selection system: the people that aren't ready for that treatment don't cause problems for other people as much as they would in other systems, they just fail out fairly quickly.