I never really did understand how someone who is an "American citizen" can also be a member of a different "sovereign" nation, subject to certain laws on the reservation and exempt from others off of it (collecting eagle feathers, marine mammal ivory, etc.). Seems pretty un-American if you ask me.
The way I see it, all the reservation tribes should be given a choice: either be a truly sovereign nation (i.e. legally and economically independent from the federal government, passports/visas needed to come off the reservation, import/export duties, etc.), or dissolve the reservation and be held to the same laws and have the same benefits as any other American citizen.
Yes, I know that the indigenous Americans had a raw deal back in the day (and arguably even today), but such is the nature of the world and its history. Stronger, more numerous, and more technologically advanced cultures have always conquered and assimilated or annihilated weaker groups of people. Thankfully, as a species, we tend to do that less frequently now (at least by military means), but how long must we make amends for history that no one alive today had anything to do with?
Besides, if one wants to see socialism/collectivism in action, he needn't look further than the American Indian reservations. Centrally planned and directed economies, individualism suppressed for "the good of the group," etc., etc., etc...