Well, I did say earlier
Some tribes are doing better at this than others.
We're as human as everyone else, with the same foibles and shortcomings.
Since the granting of "Self Governing" we've had as many scandalous episodes as the rest.
From petty things like favoritism, to serious embezzlement of tribal funds.
One of the reasons for the "indian wars" of the late 60's and early 70's, most of which took place up in your neck of the woods (N & S Dakota) was partially due to Tribal Governing bodies rampant corruption. Usually with the official backing of the BIA.
Fortunately we got smarted up pretty quick, when your elders go hungry and/or freeze to death in the depths of winter, living in structures unfit for a chicken coop. When children die of simple childhood diseases, suffer malnutrition, are poorly educated, if at all.
While the "Powers that Be" at the top of tribal government reside in expansive, expensive homes, drive big cars and show all the other signs of wealth?
Then you become just a little more attentive. And a little angry, there's been more than one serious armed conflict in Indian Country over this. To this day there are deep divisions within many tribes from recent events such as these.
(Yes Tom, it did happen, in more places than one. And not that long ago either.)