"How will the DMV system ensure only U.S. Citizens are registered to vote?
State law prohibits DMV from sending information for AB 60 applicants (undocumented driver license applicants) to the Secretary of State. For other applicants, state law requires each person to declare, under penalty of perjury, that they meet all voter eligibility requirements, including citizenship."[1]
If you're undocumented, the DMV already knows this fact and they're forbidden from sending your info to the Secretary of State. So undocumented people can't be registered to vote via the DMV, even if they don't tick the "Opt-out" box on the form (whether through negligence or malice).
If you're documented, it's perjury and voter fraud - very serious crimes for someone trying to stay legal and very easy to uncover with a simple query on the DMV database, joined with voter rolls to see who voted.
Again, do you have any proof of any of what you're alleging actually happening in the real world? I've already shown you your hypothetical scenario is nearly impossible and easy to investigate, yet you're trying to convince yourself and everyone else that "illegals vote in large numbers". Facts don't care about your feelings.
1. https://elections.cdn.sos.ca.gov/motor-voter/general-info.pd...