I thought that education was mandatory in the US. Presumably there aren't many voters who have no schooling...
(Though the idea that formal education is synonymous with education in and of itself is not at all reflective of a biased, prejudiced, and dare I say, uneducated mind, obviously.)
Usually, when people say that someone is "uneducated", they mean someone who goes to school just so that they can get a job and not to expand their knowledge and when people say that someone is "educated" they mean someone who reads a lot of books, does a lot research, engages in scientific, political, and economic discussion, etc.