Why do we have the USPS?

(Wiki - USPS)

Excuse me if my thoughts are disorganized.

OK, so according to Wiki, USPS is the 3rd-largest employer in the United States (I thought it was first). While there are of course costs to the sender of a regular piece of first-class mail, the essential mission of the USPS is to provide daily delivery of mail to every U.S. citizen for free.

This doesn't make any sense.

Let me put it another way. If you had to pay the actual cost to receive your mail every day, would you? For most people, three times a week would probably be plenty.

And then there's another issue. Let's imagine Mike in Montana who lives five miles from his nearest neighbor, and Nick from New York City who lives in a 50-story high rise. Let's assume that every American in the country receives daily mail service except these two. What is the cost facing the postal service to start delivering to Mike? To Nick? It's clearly ludicrous that these two have the same access to mail delivery for the same price.

Now, I'll be honest - a lot of my frustration has come from the fact that clearly taxpayers are paying a huge price for this service to which many are probably indifferent (at least in terms of getting mail 1-3 times a week instead of six). The Wiki article, however, seems to imply that it operates independently of the government, although this was also true of Fannie and Freddie, in that no taxpayer money went directly into the company, but that taxpayers implicitly held responsibilities if their liabilities got out of hand, which is exactly what happened. So I don't know to what extent it is the case that we all have to subsidize this service, but what I do know is that it is by government mandate that USPS, no matter how private or public it is, must deliver mail every day, and that from a cost-benefit perspective, this is clearly ludicrous.

I hope this ended up cohesive, albeit rambly and lacking a conclusion.

PS - I understand, and am not opposed to, government-guaranteed mail service for the 19th century and even parts of the 20th. Also, I guess in the back of my mind when I think about this stuff is "for what reason is it better to have USPS do Task X than to have FedEx or UPS do it?"