I’ve seen picture of US lemming already voting, How does that even work

I volunteered a few time to run a voting station in France, one of the first stuff I learned is always have two persons near the ballot box. If a dishonest person is alone, it’s pretty easy to add a few ballots in the box and sign near the name of persons who are too sick/old to go voting in person.

Logistically speaking, it’s in general not too hard to find enough volunteers (especially on a Sunday) to keep an eye on the vote from Let’s say 7:30 when the empty box is sealed to 22:30 when counting is done and you’ve signed the paperwork. But this work if the vote occurs only over one day.

I see US-Americans voting almost 2 weeks before the election, how does it happen practically, do you have enough volunteer to run ballot station for 2 weeks ? Are civil servant paid to do so ? How do you make-sure nobody tampers the box at night ?