Once something becomes political, it becomes intertwined with all the other political issues they're concerned/upset about. Everyone suffers from this to some degree; to many, the only thing they really need to know to form an opinion is their chosen party's stance on an issue.

> I still cannot understand how people understand the basis behind import controls and security for most things but blow a fuse when it comes to humans entering countries illegally

You don't understand why people see a difference between humans and trade goods?

It's simple, I pay taxes.

Spending more than most militaries on it is a breathtakingly stupid solution to a self-inflicted problem.