DrMark -
You are right - we do what we can.
And yes, there are exceptions to every rule, and rules that govern every exception.
The problem is that there is absolutely no consistency from one military installation to another, and most times no way to access "the final word" on the rules and exceptions for a specific installation until after you get there in person and play several rounds of "20 Questions" with the PIO, Provost Marshal, MPs, and the commanding officer. For me, the example of that is Quantico MCB and the variations for generally vistying the base, going to the Quantico Shooting Club, and merely transiting the base to go to the Town of Quantico - three (3) sets of rules that bear almost no relationship to each other.
Since there is almost no chance of the .gov, the .mil and the DoD ever getting together and agreeing on a single set of rules (and I'm not sure I want them to) we need to look for a repository of the rules for each location. And to do that we need folks to do the scut work of obtaining the best, verified, information possible.
stay safe.