Cali tint laws, like most other laws here, are garbage.
No tint is legal on the front 2 windows, but you can't go 2 seconds without seeing tint on the fronts. 2/3's of my cars have tinted front windows, 1 of them has really dark tint. If you're going to be driving in a area that has fog, don't get too dark with your fronts. It eliminates your best friend in fog, light. As for the front windshield, I still haven't figured out how many times you have to have been dropped on your head as a kid to do something that dumb.