Living as I do, in the western U.S. with several nearby reservations, the problem is much more complex than can be resolved in this thread. Having said that, as in much else of current life, politics (surprise) plays a dominant part. For instance... I do a lot of historical work with the "Tse-Tse'Tas") (Cheyenne Tribe to most) and beginning in about 1955 they have limited membership in the tribe (and its various bands) to those that can prove at least 1/4 Indian blood (or "blood quantum certificates"). Hence, few new, valid members have been enrolled although in many cases tribal membership has literaly exploded because within the last few decades, membership applications in tribes with newly built casinos have provided a new source of wealth. Those traditional members with proveable family descent records are shoved aside by the newly elected tribal government consisting of the more numerous new enrolees. Any resulting payment for lands, admittedly taken illegally, would result in little benefit to the tribal members at large.
Secondly, although the Treaty of Fort Laramie, signed in 1851 was primarily with the Sioux. Numerous other tribes with their various bands actually lived in or near the Black Hills (Paha Sapa, in Siouxish),many deadly enemies of the Sioux. They are not included in the settlement proposition and so, is seen as certainly unfair.
Look, like it or not, throughout history, stronger societies have displaced weaker ones, with disatrous results for the weaker... Philosphically speaking, I think it's impossible to reach a fair settlement some 200 years after the facts... but, that's said as a member of the stronger society...