It isn't that drastic. They are increasing the amount withheld by 10%. That means if they were withholding $100 they will now withhold $110. They are smart enough to increase the pain level to just below open armed revolt.
Your math is faulty. The present california rate is not 10 percent, I forget the exact amount but it is less than 10 I think. However, they are not with holding 10 percent of your with holding, they are with holding 10 more percent of your pay. That means if you make 500 bucks gross a week, then that is another 50 bucks gone from your pay check, plus whatever the present rate is. Not only that, they can expect to get an IOU, as many people did this year, when their refunds come in the mail next year. AND, they don’t say this is only for the rest of this year, it sounds to me like it is another indefinite period of time.