Without an ID, how do people at polling places know they're a legal voter?
Using the honor system made sense a century or two ago when most people lived all their lives in the same place where they grew up and everyone at the polling place knew everybody. But that's not the case now and hasn't been for a long time. With all the talk about securing our election process against tampering (which I'm all in favor of), if it doesn't include voter ID, it's not secure.
> the number of voter fraud incidents is vanishingly small
The number of known voter fraud incidents is very small. But if ID isn't required to vote and we just accept people's word when they say they're eligible to vote, how could you ever prove voter fraud?