I still think they could save an enormous amount of money by cutting much of the urban door to door delivery.
I’ve gone into town and seen mail carriers on nearly every block.
Set up urban deliveries on corners and in boxes like in apartment complexes. Of course, that would be perfect targets for little gangsta wannabes to break into and damage.
For those who don’t want their rural mailboxes smashed with baseball bats - buy two boxes, one larger than the other. Place the smaller one inside the larger one and pour cement into the space between. Your neighbors may have smashed boxes but the idiot will be easily identified as the guy who was admitted to the ER the night before with a broken arm.
Now, about cluster boxes ~ you'll still see letter carriers out there ~ the only savings is a short amount of travel time ~ a very small amount.