Social Good

In all of the various debates around the systematic assault on the US Postal Service (USPS) of late by the Trump administration, one statement crops up now and again. It takes various forms, but boils down to something like this:

The post office is great and all, but shouldn't it be self-sustaining? Things that aren't self-sustaining in the free market don't last, so if something can't be self-sustaining then it probably should get replaced by something that is (like a private company).

There's a whole lot to unpack here, so I will try to be brief, but knowing me I will fail miserably.