Do you have any factual basis for the claim a Work Permitted Alien is automatically registered to vote?
"How can a person prove his or her citizenship?"
California Elections Code section 2111 permits a person to prove they are a citizen who is eligible to register to vote by signing the affidavit of registration under penalty of perjury
Wow, an affidavit! A signed "trust me".
So a Mexican lies and signs the affidavit under penalty of perjury, and the DMV clerk in Los Angeles or San Francisco says, "Yep, good enough for me." And there are no questions asked. The Mexican isn't going to worry about perjury and odds are, he has no clue he is under the penalty of perjury if his interpreter helper doesn't tell him. What's perjury to an illegal under the threat of deportation? Except now he has a legal "work Visa", which is how he gets the CDL and voter registration. He'll sign what he is told to sign and have no clue he is under the threat of perjury.
No birth certificate requirement. No social security number. Nothing.
Just a "trust me, I honestly am a los citizeno" and clerk is "yep, good enough for me", and presto, you have another dozen new Mexican Democratic Party voters who are hand-led to the booth with a cheat sheet card who to vote for, all Democrats.
Now who in California is going to go investigate all these Mexicans and check they are not engaging in perjury? Who is even going to check their immigration status in all these sanctuary cities, to even bother finding out they lied on their Motor Voter form. Most California local politicians love the open borders. They aren't going to "profile" these illegal Mexicans.
This is a loop hole you can drive a road grader through. It makes the citizenship requirement largely meaningless when the applicant can vouch for himself, and when Democrat busloads of Mexicans can be steered into DMV offices in cities where there is an implicit guarantee there will never be any followup on these applications for perjury, unless you know something I don't about the legal requirement to investigate every single new registration through Motor Voter.
And when I said, "automatically", I simply meant that there will be a concerted effort by their Democrat handlers who go with them to the DMV office to walk them through the Motor Voter registration at the same time they get their shiny new CDLs. Not automatic by DMV, but automatic in practice. There is no way the Democrats are going to miss an opportunity to register all these illegal Mexicans to vote. No way.