When I was in High School, I worked first at Arby's and then at Pizza Hut (they were also next door to each other). To work at Arby's, I had to purchase the uniform I was to wear (about $25), but when I quit and went to Pizza Hut they gave me the uniform to wear.
Why did Arby's charge me for the uniform, while Pizza Hut did not?
Arby's paid a higher wage, but they were not exactly the same type of food service so it is hard to determine if that means anything. Let's rule out "worker exploitation" because it is ridiculous, it was a competitive labor market and I could have gone other places, I went to Arby's because the wage was higher, I quit shortly thereafter because it was a disgusting place to work (at that particular franchise store, I still ate other Arby's).
My guess is that Arby's had (has?) higher turnover, so they use the uniform cost to discourage workers who do not expect to work long enough to recoup the cost of the uniform in higher wages. It would not be a useful deterrent afterwards as it would be a sunk cost, but it may have helped with the self-selection. Thoughts?