Yep, the people of Tijuana aren't happy to have this drain on their local system. I saw an article too. It talked about how they're fleeing violence about at the same rate of Detroit or another major city (can't remember) and how this is clearly simply an economic driver for them.
I also saw quotes in another article where some are talking of hopping the fence en masse and overwhelming the border patrols. That sounds kind of invade-y to me. One guy jumped it and then went back to show he could. Sounds kind of entitled to me. The whole thing just seems odd.