Can someone tell me why...

Requiring an ID to vote is discriminatory?
No scratch that, of course it is discriminatory.
It discriminates against people who are not citizens of the locality to vote.
It discriminates against those who are not eligible to vote due to their criminal record.
It discriminates against those who might attempt to vote in precincts they do not live in.

So tell me, why would someone argue against providing a valid ID to vote?