It's fairly meaningless. The reservations have never operated under the same set of laws that the rest of the US does. In many ways they were already nearly soverign countries, even the federal penal code doesn't totally apply to them. (Someone once cynically observed that the CIA doesn't need to transport people to foriegn countries to torture them, just to a reservation.) And honestly, they suffer for it.
I could also cynically observe that much of it is their own damn fault in persisting with the reservation system long after it became obvious that it was hurting them. There are other ways to retain your identity besides walling yourself off, which is the option they chose. Calfornia's local tribes (they prefer "band" normally) have benefitted, perhaps, but few others.
