Yes. If you are a convicted felony, you lose your right to vote until you get out and request to get the right back from the state. Each state has their own rules. Some are automatic and some are a pain in the ass.
Some states also have been known to purge voters from their database sometime before an election. They claim it’s either an error or just getting rid of old records of deceased voters. No one believes them though.
I’m just guessing, but they would know the serial numbers that got stolen. Let’s say 1230001-1231000. Out of those 1000 tickets, the company that makes the tickets, could look up what the big winners were. If there was something like win $10,000 then that would be easier to flag, because they don’t get cashed out at the gas station. If there was small winnings like $5-$10, I could see the scratcher company just writing those losses off.