You think the USPS still delivers to all individual front doors or the mailbox at the end of the sidewalk?
What are you talking about? They don’t.
Horse manure look it up
Any neighborhood older than say 1978 is going to have individual mailboxes (like my neighborhood)...and neighborhoods older than 1965 or so will have mail slots in front doors or mail receptacles near the front door. Lockable “CBU’s” (cluster mailbox units) were not a “thing” until about 2001. (some unlocked CBU’s were tried for awhile before 2000). Really rural addresses (like my Mom’s) have private “contract rural mail carriers” that deliver to individual mailboxes in private (usually right hand drive) vehicles.
https://nationalmailboxes.com/news/centralized-mail-delivery-a-history/