If it was at food stores, gas stations etc. near the brothels, it could very well be the brothel employees and/or their families who are working off the books or otherwise fudging. I’ve never been to Nevada, and could wrong, if course. But see my earlier post. Prostitution and welfare shennanigans seem to go hand in hand a lot.
According to the book Mustang Ranch, a lot of the girls were married or cohabiting with families who lived close enough to visit.
These were Indiana residents, or at least covered by food stamps and TANF through the state of Indiana.
I’m thinking they were on “holiday”.