Aren’t these illegal?

I always thought that these were only legal if they were giving out store credit or something other than cash. I looked it up and the law does stipulate that you can’t give out anything that can be exchanged for cash. These are using vouchers that you exchange for cash so what’s going on here? This bar / restaurant has been around for years and is very popular so surely it’s legal if they haven’t had any issues. Just wondering how. This is in Allen