A paranoid individual might claim that this ink could be tampered with or replaced with washable ink.

Can the same argument not be made for requiring voter IDs? youeseh I'm replying to says it's "few numbers" adding up. Another thread from sverige in this tree links vox and nyt saying that requiring ID has small numbers effect of turnout. So saying that their concern of voter fraud is a small numbers thing kind of lacks heft as an argument.

If these are both the case, then why not go with the requirement (and possibly make the requirement "easier" by issuing IDs at the same time/place) so there's no possibility of contesting the election results with regard to this particular issue?