That's the normal process. People behind you or the poll workers could see who you voted for if it showed on the screen. Any mass irregularities should hopefully show up in random manual counts that verify the machines are working correctly. The machines also store a photo of the ballot.

For a majority of states, when you vote in person you personally scan your ballot in after marking it, and your vote gets counted and registered in the system immediately. Your ballot could still be misplaced after that, but that would only matter if there was a recount. The machines might save a picture copy of your ballot when you scan it too, but I'm not sure about that. If they did a recount and there were a lot less ballots than originally scanned, that would definitely raise red flags.