You have your facts wrong again.
They have borrowed $15 billion from the US taxpayers so far-
"The service -- one of the few government agencies explicitly authorized by the Constitution -- has reached its $15 billion credit limit with the U.S. Treasury and has effectively run out of money, said Williams, whose job is to prevent fraud, waste and program abuse and promote USPS efficiency.
"This is the year that they borrowed so much that they can't borrow anymore," he told the newspaper."They will probably get bailed out soon or receive additional spending limits. In my book, it's effectively a tax and will only get worse.
About the unions- you say they are a necessary evil, I halfway agree with you: They are evil.