Automation changed the mail delivery business a lot in the 21 plus years I was a carrier (retired four years now). In the 80’s most of the mail was sorted to the carriers in-office, so incomplete addresses were more likely to be delivered. In our small office it was common for a clerk to shout out “Who delivers Uncle Moose?” and a carrier would claim the piece because he knew that Uncle Moose and Aunt Patsy lived on his route. Now most mail is put into delivery sequence at a remote plant and the carrier doesn’t even see it until he or she gets to the delivery point.
Also, you’re far less likely to have a regular mailman. The USPS is maximizing the use of casual labor to deliver mail, and often, on a light day the regular carriers are required to ‘pivot’, that is, take sections of another route that someone else put up. They won’t be as familliar with the residents on that section.
As a practical matter, the mail used to get to the carrier by ZIP and street address and the experienced carrier delivered it by name. Now it’s more a matter of numbers.
If I recall correctly - in the Netherlands you used to get a letter delivered just by writing down the housenumber and the zipcode. Our zipcodes consist of four digits which identify the town/city followed by two letters which identify the street (in fact even what side of the street)…with more and more housing development I’m not sure if that concept still holds up these days.
Until about three years ago my local post office had a slot for “local mail” that wasn’t going outside the city. It’s been removed now. 
At my post office (and I’m told at many others) there are separate slots for “stamped mail” and “metered mail”. They both dump into the same bin. I have no idea why they do this. They can’t use the excuse that they had the two separate slots before and then combined them, because this is a brand new post office.
Metered mail is subject to fewer security checks, so I’m guessing there’s something in between the stamped mail slot and the bin that isn’t in between the metered slot and the bin- like a scanner or somesuch.