Been driving in Nor Cal for almost 30 years and half-a-million miles, never had a front plate on any of my cars, only 4 no-plate tickets...
Got 1 no-plate ticket in SF recently while parked. Also got a didn't-curb-wheels-on-a-3%-or-higher-grade ticket...silly...firstly, who knows what a 3% grade looks like?! Second, that car has a manual tranny and I parked it in 1st gear, and the handbrake works well and I used it...it was not going anywhere.
2 no-plate tickets in Berkeley while parked, and was pulled over once for having expired reg tags.
1 no-plate ticket while pulled over for speeding.
Never got pulled over solely for not having a front plate, but did get harassed by the Mt. Lick Observatory 'cop' as I was trying to pull out of the parking lot one-time (he proceeded to insult my WRX and claim that he almost got knocked off the road by somebody coming at him down the middle of the twisty roads driving a WRX just like mine -- it was mine, and no, I didn't come anywhere close to knocking drama-queen cop off the road).
I paid all tickets, but the $124 SF ticket I put the plate on temporarily with double-stick tape and got it signed off.
I don't believe the rate goes up upon multiple violations -- the ticket price is set by the city and it is printed on the citation, unlike when you get a moving violation for which they mail you a notice later on the cost.
So, I will not bother putting on the front plate unless I'm heading to SF and know that I'll be parking on the street