In the post Howard Hughes era it was all about the skim. That ended with publicly traded shares and oversight. A privately owned casino like the Cortez would give someone with a shady past an opportunity to make a legitimate investment and "clean up" money, similar to investing in a restaurant or anything else, but that's about it. Kirk Kerkorkian was actually the one who came up with the idea to make casinos so big and with so many employees that it would scare off racketeers. More employees means more social security numbers means more attention from the IRS means more oversight. Not ideal for a group that's trying to keep things quiet. They'd prefer a hundred or so employees who they could know and "trust" (know better than to talk about who they see in the place, or the loose teeth a janitor was sweeping off the storage room floor).