I didn't read your link! Maybe I'm totally wrong!
I frankly don't think that has anything to do with PSI, Or I'm misunderstanding what exactly your saying in respects to the "R" word!
PSI is a company that has sold their business to many states, it doesn't mean they or any individual state just accepts them as a proof to something else, or for someone else! It's a business!
I beleieve, you've forgotten what make US up IE, "State's" would be the word.
The State Laws are for that State, it's frankly always seemed a little wide open west of the mississippi (from reading here) but that another thread.
Why have the Fed in something the State has their hand on, well that debate can go on and on, too...
Maybe you are correct there should a national system.
I can only relate it to the national teacher certifiction, but that doesn't stop the final acceptance of various classes, and colleges, etc., and is still by a state official and their legal state status.
Sure you can present your papers, but the individual laws will still govern and yes they still need to look at it!
Besides all that, some State don't qualify to other States in respects to how they manager there own State, in respect to each others Status and Laws.