Everyone is misunderstanding this. Yes, everyone will be automatically registered to vote when they get a driver’s license, but there is an ‘opt out’ provision. Naturally, law-abiding illegals (wait a minute, what?) will opt out. So there’s no problem here.
I think that CA drivers license folks already had opt out for voter registration. So anyone who voted as a non citizen and got caught could just claim that they didn’t understand the language that they signed. The number of illegal VOTES (not just illegal people voting ) in 2016 probably was in the millions.