Not really a rhetorical question. Why postal voting rather than voting in person? A matter of convenience? Difficulty in locating and getting to a polling place on Election Day? Finding time to vote on Election Day (if employers didn’t allow you to go)? Long lines at the polls? Which reasons, I wonder?
Follow-up to this.
California had problems with mail-in voting even during its 2020 Primary Election.
https://www.pbs.org/newshour/nation/california-rejected-100000-mail-in-ballots-because-of-mistakes