I listen to people play in the bart/muni stations. I've talked to them, and they like doing it, not for the money, but for the accoustics. If they wanted, they could go up one level, to the cable car turnaround, and make a lot of money, but if you are playing for commuters in the AM, people have places to be, people to do, butts to sniff like any other dog.
So a lot of this is a fake set up. Washington D.C. is one of the most competitive places on earth. If you want to show up late for work, you really want to be working on your resume.
I take the time to listen, when I have the time. But if I'm on my way to a show, I'd run over your grandmother not to be late.