"Parking should be free" is an interesting discussion point. Leaving out the issue of promoting turnover, it seems reasonable to me that a municipality should be able to charge rent for storage of private property (i.e. my car) on public property (i.e. the street).
On the other hand, I also grew up in an area with ample free parking, so I certainly understand the visceral annoyance. To me, the convenience of being able to pay with credit/debit cards (rather than having to hunt the seat cushions for loose change) might go a long way toward mitigating that effect, though.
Does San Francisco not have pay by phone parking meters?
We've had them in Vancouver for awhile now, and it's so handy (after you setup an account the first time). They text you 10 minutes before your meter expires and you can just call and add extra minutes if you're going to be longer than expected.