The American Middle class wants something done about illegal immigration. The liberal elite want to use naturalized Mexican and other Third World illegals as a reliable voting block and political clients, much as they use blacks. Meanwhile, a substantial number of Republicans serve the interests of business elites who want the cheap labor. So as is usually the case, America's Middle Class gets stabbed from both sides of the aisle.
In the case of liberal Republicans like Jeb, I think it's a combination of cheap labor lobbying combined with muddle-headed thinking about "compassion."
Everything in your post makes sense... and nice 'summation'. You 'get' Jeb...