I used to work in an industry and area where a huge portion of the support services (custodial, labor, etc) were provided by tribal contractors with predominant

I used to work in an industry and area where a huge portion of the support services (custodial, labor, etc) were provided by tribal contractors with predominantly Native American employees, providing huge employment to these often struggling communities because of preferential selection. So there are definitely anecdotal success stories to these programs. There is also the opposite, though. There are some controls in place. For example, my understanding is that in the federal government, contractors that are preferentially selected for various reasons must perform a majority (at least a technical majority, e.g. 51%) of the work in-house, although I don't know a lot about how that is measured or supervised so I'm not sure how effective it is. I have certainly seen cases that looked like abuse.