The theory is if you are at least a resident, you can vote on local issues, but not federal ones, like the prez.
Whether you agree w/that or not is besides the point I’m making.
As far as I can tell, an illegal who is a resident that goes to vote does NOT get a ballot different from anyone else. There will still be a check box for prez.
There is also NO personally identifiable info on the ballot.
So if an illegal who is resident votes, they are able to vote for prez because they get the same ballot as everyone else, and it gets counted because there’s no way to tell from the ballot that the person was only allowed to vote on local stuff.
Interestingly, if CA actually used their drivers licenses for ID, then “undocumented” residents can be identified... but think if the (D) vote loss.../S