I don't know any nation-wide statistics, but there was a study done in Texas that showed that one million of the state's 13.5 million registered voters did not have photo ID. If you extrapolated that nation-wide (this is rough mental math), you'd have about 20 million registered voters without photo ID in the United States. That's a lot of voters.

And yes, maybe you don't really care what they think if they're too lazy to go get photo ID, and I don't think you'd be alone in that line of thought, but it's still true that this portion of the population is under-represented partially as a result of such laws. So the question is, do you want your government to be fully representative of the interests of all its citizens, or only of the ones who have the time and energy and drive to be involved?

I'm not even American, so I can't answer that question. But it seems a little iffy to me when laws like this are passed by people who know damn well what the results will be ... and by complete coincidence, such laws are usually supported by the party that poor people vote for less often, and opposed by the party that poor people vote for more often. I personally feel that effort should be made to give everyone the best chance at voting, but I definitely acknowledge that a compelling argument can be made the other way, in the vein that you're talking about.