Think of it this way as well:
State can't tell you how to issue your permit in your state, but they do have the power to tell you that you will observe and obide by permits issued in other states. Best example, driver's license. They will not tell a state, "You need to have a 25 question test." That's up to your state to decide. But, they can say that you will recognize permits from those out of state. Moreover, just like you can't just go next door to a new state and apply for their license while being a resident of another state, you cannot do that here.
If I can't get a driver's license in Hawaii because I can't pass the test, then I cannot just go next door to get one. I'm not sure if that helps some people, but this is pretty much how it would work.