What’s the deal with all the 24/7 video stores?

I've lived in Houston all my life and have always wondered why we have so many of these 24/7 video rental stores around. What go's at those stores? I assume its just drugs trafficking, and prostitution. If that's the case, why a video rental place?

I would love to hear from people who work at some of these. Or people who have visited these stores, and share your storys. Please.