“The very immunity from certain laws that they enjoy exists due to U.S. jurisdiction does it not?”
Just to clarify, the three categories I mentioned did not arrive by their qualified immunity through statutes or anything like that (though, certainly, there are statutes covering them). They are of another sort because of the underlying nature of their relationship to the U.S. government. Which relationships are in each case fundamentally different from the relationships that exist between the U.S. government and regular people who happen to reside somewhere under its authority, be they interlopers or legals.
First, diplomats have immunity because they are official envoys form other nations, and there is a whole long diplomatic tradition predating its existence to which the U.S. subscribes.
Second, invading armies and hostile forces just aren’t like everyday illegals, and I don’t think I have to explain why.
Third, Native Americans’ occupation of what is now U.S. territory long predates the existence of the U.S. Our government has always had a special relationship with them. Never, ever, was it assumed that they didn’t have their own form of sovereignty, even if we did decide their fate for them.
All acceded to by U.S. law.