It would NOT be unprofitable to the USPS, as outlined in the article i cited. You essentially cite your ideology as a critique of USPS, but your ideology has zero to do with REAL WORLD prospects for a fair and just finance system that supports RATHER THAN PREYS ON people at the bottom of the engineered pyramid. The USPS has been undermined by your ideological allies in the duopoly for decades. That's the real story of the USPS.
Of course you can't allow yourself to think that the pyramid is engineered. We're all "free to choose" and the fact that there were intensive lobbying campaigns by the vultures, and as a result laws were explicitly changed to allow the explosion of "payday lending" vultures to proliferate, you can only see that as an advance for freedom, not an advance for looting. You can't see past your ideological blinders to even acknowledge that the billions of dollars the looters have poured into think-tanks and "campaign contributions" over the past decades have anything at all to do with the tilted "playing field" that your "free to choose" impoverished face. Or on a related note, to even acknowledge that the massive, multi-billion dollar ideological campaign by agents of concentrated wealth promoting the "privatization" of the commonwealth, has anything to do with the state of the USPS. It's just permanently and inherently "inefficient" even though it is ACTUALLY and has always been FAR MORE EFFICIENT at delivering the mail than any of the private corporate providers. Just as Social Security is far more efficient than any private retirement program, and Medicare and the VA are far more efficient than any private health care insurer or provider. Reality has no meaning to you.
Credit Unions are also far different from what your knee-jerk ideological assumptions allow you to contemplate. Credit Unions serve virtually every community in the USA, and in fact more and more CUs ARE setting up non-predatory "payday loans" and check-cashing services that are designed to provide consumers a leg up and a way out, rather than a heartless spiral into further debt.
And perhaps YOU would be so kind as to outline how it is of genuine benefit to anyone to pay (falsely represented) interest rates and fees that work out to hundreds of percent for small loans. Seriously, in real-world terms, not simply recitations of your ideological assumptions: How is ANYONE but the vultures "helped" by these predatory vultures who extract BILLIONS OF DOLLARS OF WEALTH from the poorest households in the USA?
And how is the standard practice of the false representation to desperate consumers, of the cumulative impact of fees and interest, consistent with your vision of "freedom"? Free to Lie?