In the state of Washington (not to be confused with the city of Washington; our largest city is Seattle), everyone gets the chance to vote in the privacy of their own home even weeks before the election and mail in their ballot, or drop it in a drop box. There is an outer envelope one signs and an inner privacy envelope which is left unopened until the count starts. It's possible that there are hidden shenanigans, but if there are observers for the vote-counting process I can't imagine any problems.

I have no idea why other states don't do this.