I agree the issue should seem to be more about who is getting ballots. Here we just have a couple of simple steps in order for your ballot to be counted (self certification, signature, privacy sleeve, and sealed envelope.
It would be very easy for someone to steal my ballot and vote on my behalf. But we have been doing it this way for a long time here, and I don't know of any systemic problems.
I also hand deliver my ballot to the polling place.