Short post...This is a pet peeve of mine. Piss poor planning of laws.
As an example..a drivers license issued in NYC is valid in every other state of the Union. A marriage license issued in San Francisco is valid everywhere else in the U.S. So, even though the state driving laws in Hawaii are different then in Michigan, Michigan is forced to recognize a visiting Hawaiians license. A gay couple married in San Francisco is valid in Arizona, even though Arizona does not allow or recognize gay marriages.
Yet, as a law-abiding gun owner who has taken a multitude of training classes and am certified CCW in Arizona, there are only a handful of states that recognize my licensing outside of Arizona. Yet, if i was a police officer, current or retired, I could carry in all 50 states without issue. I guarantee, I am a better, more consistent shot and have more actually training then any standard cop on the streets who is not on a specialty team; such as SWAT. I have been at the range with some of my officer friends, and their lack of control and consistency are a bit scary. I have shot tens of thousands of bullets in the past twenty years, how many cops can say the same? I have well over 100 hours of classroom and another 150 hours of range training under my belt...can a beat cop say that?
The point being, there needs to be a countrywide training and certification. End of rant.