It disproportionately affects the poor who have trouble with transportation and scheduling to get a photo ID (since they may not be drivers, and therefore previously may not have had the need for a photo ID), and also the elderly, whose birth records may be difficult to find. It obviously doesn't affect those who regularly have up-to-date photo IDs, say, because they already drive everywhere.

If we offered same-day voter registration at every polling place, or had automatic voter registration by virtue of some other government process, this would be a non-issue.