A lot more than the issue of migrant or non-citizen voting, which isn't happening at all and will never happen.
Think about it this way: how much would someone have to pay you to illegally vote in an election for you to do it? You cast your vote in a precinct where you live. Then this person tells you to travel to a different precinct and vote there under a different name, all spelled out for you.
Would you do it for $10K? $100K? Let's say you're easily bought and it's $10K. Now, let's see how this works out for the payor. He's got $1M he wants to spend on influencing elections. With that $1M he can buy . . . 100 votes. In other words, not enough to sway any significant election in NC that I remember. Even the state supreme court cases are being decided by a few hundred.
Well, now the person commits $100M to the task. With that, he can buy 10K votes. All right, that's possibly enough to sway an election. But which election? The presidential race in NC? It *** could have been *** decided by less than 10K votes, but actually it wasn't nearly that close. That's $100M down the drain. A House race? Which one?
Oh, and there's a logistical problem. How do you hide this? Suddenly people all over the area are buying new cars or appliances or whatever. Maybe they just buy a round of drinks for everyone at a bar. In any event, are we going to assume that none of these 10K people are going to have loose lips. If word gets out, there will be an investigation. This payor would be facing a very lengthy prison sentence. Imagine going to prison for paying $100M out of your own pocket for a chance at maybe getting something you want (which is itself of limited benefit, since there are many legislators).
NONE OF IT MAKES SENSE. Which is why it doesn't happen. Nobody has an incentive to risk jail time to cast a vote that is 99.999% likely to be meaningless.