In the U.S. where it is underfunded and slowly being rebuilt after being destroyed in the 1950s? Or in Tokyo where millions take it without trouble every day?
I'll be bold enough to say that PRT could not physically accommodate Tokyo's or London's or New York's population of commuters (or even those in Los Angeles).
And really? That "we're so special, so there's no comparable model" is an evasion. If you can't build a model of how PRT would work in Los Angeles or Denver or Minneapolis or Kansas City, how can you be trusted with a real city?