Lots of Mexico flying out of DFW, tends to go junior because people normally don't like it. Flying international for a regional, Canada and Mexico normally is a hassle combined with the crime and stuff in Mexico and people don't rather stay on US soil. We haven't had issues with crew safety that we know of but people still rather not do it. Same can be said for Canada trips out of ORD.

I don't fly out of DFW so I can only go by what people say.