In person voter fraud requires a large base of conspirators who are never caught, committing a federal crime on behalf of a political actor who also needs to somehow incentivize them to do so without being caught.

Whereas suppressing turn out just requires making it difficult for someone to have a bunch of ID they normally don't need on them in any part of their lives.

These laws are never just "photo ID" - they're always a box truck of weird edge rules about the type of ID.