In person voter fraud simply doesn’t happen. People do not show up at the polls pretending to be someone who they are not. It’s not hard to see why. For most people interested in voting, they are registered and can cast their own vote. Who wants to risk scrutiny by returning to the same polling place to cast a second vote under a different identity?
Well, maybe you might want to go to a different polling station and cast a second vote there. But now you risk running into someone who knows the person you are impersonating. After all, you don’t live in that precinct. You might even run into the voter you’re impersonating.
In order to pull off in person voter fraud, you have to know that the person you plan to impersonate hasn’t already voted, isn’t known personally by the election officials, and you probably want to make sure they aren’t planning to vote either, because that could arouse an investigation if the records show that someone has already voted under their name. The most likely situation where voter fraud would be plausible is when someone decides to vote for a family member who has recently died. But even that is complicated by the aforementioned considerations about voting twice in the same district or running into someone who knows that your relative is deceased.
There are criminal penalties for voter fraud, and that makes it nonsensical to commit the crime when so few elections are decided by one vote. Voter fraud would only make sense if it were carried out in a very widespread way so that dozens or hundreds of votes were cast. Anyone considering such a widespread conspiracy would either attempt old-school ballot stuffing or try to penetrate the electronic vote-counting machines. In person voter fraud would be a very flawed, inefficient, complicated, and high-risk way to change the outcome of an election, and the people who attempted it would have to expect some very serious benefits in return.
These are the reasons why no one tries to commit in person voter fraud.