Why can’t we just vote in person? Voting is already socially distant. The line will be longer because it’ll be four to six feet apart. It’ll require some police presence to help manage it, but the wait time will not be changed at all. If McDonalds can open up their dining rooms in a socially distant manner than there is no reason why each state can’t get the proper logistics in place.
Vote by mail makes it much easier for the average person to cast their vote. It allows a voter to cast their vote days or weeks in advance from the comfort of their own home.
If states reverted to in-person voting, they will be staring down very long lines on election day. Some may simply choose to not vote if the wait is long enough and others wouldn't vote if their employers don't pay them for their time spent voting.