My kids and I participated in early voting for the TN primary this week. They had poll workers behind plastic. You put your ID on a platform and it was scanned electronically to show who you were. A ballot card was slid under the plastic along with a small wooden stylus you could use on the voting machine. Once finished, you put your ballot card in the ballot box. No contact with anyone. There's absolutely no need for mail in ballots.

Side note - my daughter was a first time voter so they had her stand in front of the flag with a congratulations sign and take pics. All the poll workers stood up and applauded. Gotta say that was a really nice touch.