I'm certainly not one of those families; my kids are typically transported like little mafia bosses in the back as they plan their crimes.
My older kid, though, started going to a new school, that's quite far away and he walks down to the train station, gets on the train, gets off at the end of the line and takes a light rail subway 2 stops to his school. It's terrifying, as a parent, to send him off like that, but it's been wonderful for him and he's grown tremendously.
The most dangerous part of that commute, btw, is crossing the street to the train station -- it's 1/4th of a mile from my house, but that specific crossing kills a person every 18 months, almost to the day, and has for the past 15 years I've lived in this neighborhood. Any talk about fixing the problem, especially if the fix may inconvenience drivers, will provoke such rage as you wouldn't believe from otherwise seemingly sane people.