Yoni's point reminds me of a minor bruhaha which erupted during my freshman year abroad. Suddenly, our neighborhood pizza joint closed for a week; when it reopened the tables had beeen removed. Why? The local kosher mafia had decided that it was unseemly for men and women to sit together, and had put pressure on the owners to eliminate the table seating that made it possible. According to the owner (paraphrased from memory and translated) "The Supervising Rabbi told us that if we didn't remove the tables he'd yank our kosher certification."
What does kashrus have to do with ethics? Nothing according to Avi Shafran and the two, like oil and water, must never be mixed. Still, they do mix, and are mixed. (Strip clubs - no matter how perfect the food - aren't given kosher certifications.) And if the power of the kashrus organizations can be used to enforce modesty rules, why can't they also be used to defend the rights of workers?