Generally people with adequate jobs and income also have a whole collection of documenation to go with it.
What constitutes proof of residency for example? Receipts for rent, mortgages, etc. usually; sometimes utility bills. guess what students and poor people are less likely to have? Or, they move so often and don’t haul a trunk full of papers with them, keeping a year or two of old bills and other papers. Guess who’s less likely to have the income to own a car, and so have the drivers’ license? (Or unless they are diligent, the address is out of date). Who’s less likely to have a passport to go on vacation outside the USA?
there was a news article about one lady in a state that just passed a voter documentation law who was born in Peurto Rico. To get the necessary documents for voter registration (no drivers’ license) she needed a birth certificate from some small town in Peurto Rico. She needed to spend a lot of money (for her) and it likely would not arrive in time for this election’s deadline; assuming the PR birth records people will send a document to anyone who asks from half a continent away.
Whereas the richer types would probably find no problem in spending say, $50 or $100 to get a document from somewhere; and have the phone to call long distance, a fixed and verifieable addres to get that document mailed to them.
it’s the relative cost to them of regular documents too. if the average middle class person ahd to shell out the equivalent of $500 for the privilege of voting, how many would? Do you think a driver’s license is cheap for someone who can barely afford rent and does not need one, and probably can’t find a car to practice or get the road test?