[depressed]

If you look at the mass mailing options that the USPS markets on their website, they ask you to basically buy a whole delivery route at a time.

There's no routing and sorting they have to do. The carrier just picks up a stack of letters at the start of the shift, and drops one in every mailbox.

The labor cost that the USPS has to put in for a mass mailing is a fraction of what it has to do for normal mailing.

[TuringNYC]

There is another cost - the cost to society of paper garbage and dead trees. I live in a 200+ unit apartment building and recently received a mailer for hedge cutting. I promptly went to the mailroom recycling bin and threw it out, discovering about 150 identical copies thrown out by other unit residents. Obviously no one in a building needs hedge cutting — we live in apartments, not houses — but the mailer didn’t care or put much thought into even basic ad targeting. What a waste.