Your signature is your ID.
When you register to vote, your signature is placed on file.
When you go to vote, you sign in and your signature is compared to the registration.
If it matches, you can vote. If it doesn’t match, you can prove who you are or cast a provisional ballot pending identification.
I’d think the signature would be way harder to fake than an ID. Nobody signs my name like I do, but I bet there are plenty of bad ID photos that kinda/sorta look like me.