entombed in the shrine of zeroes and ones

I don't think the government granted them casino licenses as much as granted them sovereignty and didn't back down on that grant when they created a venue for something the government has outlawed as vice. The reasons for which indian reservations are not hotbeds of prostition, drug production and slavery are, one presumes, reasons of the Indians alone. (And their desire not to put test to the circumstances of their existence.)

Heck, in the case of slavery, we might be compelled to act regardless of Indian sovereignty. In that respect, some moderation is its own act of self-preservation.