Where do you see the problem? It all depends on how many people SF employs to check for parking violations.
100 tickets a day should be certainly doable in congested regions.
Hell, if you'd ticket bicycle riders over here, you could do 100 tickets in an hour.
(I use them myself, but I really, really despise the entitlement of some riders, who simply can't work 100 metres and instead park in zones reserved for fire fighters and emergency cars.)