Well, it turns out millions of Americans don't have photo ID. Most of them are older, minority and poor people. For some it's a hardship to get a photo ID- both financially and physically. People need documentation that proves their birth to get a photo ID and some people don't have birth certificates or a way to readily get one. Even states where photo IDs are free (see Texas) require people to get a birth certificate (money) to get it and often a trip to a centralized office that poor people without transportation can't get to. The photo ID law in Texas was recently overturned for this reason. The Brennan Center for Justice has well documented that there are lots of people without photo IDs and that they are disproportionately people who are minorities, poor and elderly. Furthermore, they tend to vote Democratic. Requiring people to pay money to get an ID just to vote is equivalent to a poll tax, which is illegal. Poll taxes, the grandfather clause, literacy tests, etc. were all methods used to disenfranchise specific sectors of the electorate in the past. None of these methods ever mentioned race, yet their intent was clear.
There is a good reason why these laws are popping up now and being proposed by Republican governors and legislators- there was a surge of voters they'd rather not have voting in 2008. That's why Republicans are for the laws and Democrats are against them. We all know who would be most impacted by them.
On the other hand, Republicans argue that there could be massive voter fraud at the polls and the potential for voter fraud (without any evidence of it) is reason enough to take the risk of disenfranchising legitimate voters and/or spending millions of dollars providing them with picture IDs (which will never happen between now and November 6th). I find it to be a weak argument since we know the law would eliminate the votes of thousands of voters and we don't know that it would prevent any systemic fraud. In fact, in a lawsuit against it, the State of Pennsylvania stipulated they knew of no voter fraud going in their state or any other state. Furthermore, in a moment of frankness (or maybe he thought no one other than Republicans were listening), the Speak of the House in Pennsylvania declared the voter ID law a victory for Mitt Romney.
We've been down this road before and we know how to read the signs: