They've been doing that for years. Too many people put trash in the mail boxes, or wasps build their nests inside. And there is less and less personal mail being sent. No business in Manhattan is going to be using the mail boxes. If they use mail, they are going to pre-sorted by mail route to get the cheapest bulk rate.
At Central Washington University they were campaigning for pre-paid ballots. While students registered in Kittitas County could put their ballots in the ballot collection boxes, students registered elsewhere had to mail their ballot (or drive home). But no students had any stamps. If they went to the bookstore, they'd be laughed at and told to go look over next to the buggy whips and 8-tracks. Those pushing voting were given permission to give away stamps, and USPS did put a temporary mailbox on campus.
