To vote in person: Just go in, line off your name, grab a ballot, fill it out and put it in the reader...
To vote by mail: Randomly receive a ballot you don't ask for in the mail, make sure your mother-in-law doesn't fill it out for you, fend off all the party machine cronies who come around to your door asking to buy it from you for $100 or otherwise threaten to take away your social security if you don't give it to them, then fill it out along with all your private information on the envelop, then put it in the mail box hoping your mother-in-law or those people at the door aren't waiting there to destroy it the second you put it in, then hoping the post office people don't see your name on the envelop and destroy it, then hoping the people you're voting against who are receiving and processing it don't see your name on the envelop and destroy it, then waiting 5 months after the polls close for the people who lost to create a mail-in ballot for everyone on the registration list who didn't vote.
Yeah. Maybe mail-in ballots are easier and cheaper ... for people in power to stay in power.