It's pretty common for poor people, disabled people, people of color, and college students to not have the proper ID needed to vote. Sometimes people don't have their birth certificate needed to get ID and the fee for replacing the certificate is too high. Some people live in very rural areas where the nearest licensing office is far away or only open once a week.

I believe a different comment addressed the practical difficulty of getting an ID. I would like to address a different point. In democracy, voting is a right with very few restrictions (age being one of the few). Caring about politics should not serve as a condition for voting rights. Many surveys have indicated that the vast majority of Americans have quite apolitical views, but obviously they should have the right to vote. If a country restricts voting rights to those interested in politics, its political representation will overly favor those educated and wealthy (since they are more likely to have the time to care about politics). This argument does not mean that one should not care about politics. Ideally, voters should pay attention to politics. I also agree that sometimes a lack of understanding in politics probably cause voters to make bad decisions. However, when compared with the alternative, a scenario where political understanding is mandatory for voting rights, I would argue the current situation compares far less harmful.