We don't cut off the lips of particularly offensive liars and noses of adulterous women. (Or was it vice versa?) Not that all tribes were into mutilation certainly, but none do it now. And if someone did try to reinstate those old-timey values in his family, modern medicine would be able to rebuild their faces, so that's also kind of a nice thing.
Apparently, though, indigenous tribes mostly did get the idea of chattel slavery from us. Although other forms of slavery were normal in North Amerca before the advent of Europeans, the idea of selling their slaves as commodities really picked up once Europeans provided markets where captives from tribal warfare, unwanted whomevers, and escaped black slaves could be sold for money.
But as for being absolutely sure the tribe would never develop or extract from this land, give them a break. These are PEOPLE. Real people who think real-people thoughts, do real-people things, and have real-people needs. Like feeding and sending real kids to college, and other sacred duties.
Just for one reality, casino gambling is the single most successful source of income for tribes in general. The Apaches may not be as dependent on casinos as some other tribes are, but internet gambling is posing a real threat to the economic futures of those that are. What next?