We don’t have carpool lanes in Chicago, as we haven’t officially entered the 90’s yet. (We entered the 80’s in 1994 with the introduction of curbside recycling and the 70’s in 1987 with the advent of cable TV. So we’re gaining.)
I think they’re a great idea. One point that hasn’t been made yet is that in this country people get to decide where they live, and where they work, at least to some extent. So, if your home & work location prohibits you from carpooling, you can change one or both, if it’s causing you a big problem.