A huge fraction of people (again, poor people, whom I’m sure you’re too privileged to associate with) do not file taxes and are not required to file taxes. See we’re getting into that thing I mentioned earlier where I give a thousand examples and you individualize each one.

How would an illiterate dude living in a cave register to vote?

If he knows his date of birth and his social security number, he can register in California. If he doesn’t know his SSN, they can look it up for him. In Texas, he doesn’t get to vote.