“It seems to me that Mail In Ballots ought to be handled by the USPS, utilizing its conveyances, i.e. mail boxes.”
I’m not for any type of general mail-in ballots. ONLY Absentee ballots that are requested by a specific person for a specific reason (i.e. you’ll be out of the area on voting day, etc.), and that are signed and dated on the serialized ballot itself and on the outside of the generic (non-party-specific) serialized envelope.
With all it’s vaunted equipment, checks still get lost in the mail, we still find boxes of mail dumped in dumpsters, and there are usually reports around election time of mailpersons removing Republican votes and processing only Democrat votes (not so much vice versa) (where the ballots can be identified as such).
In my opinion, the USPS has proven itself untrustworthy to handle massive amounts of mail-in ballots.