Fair point. I'm a USA citizen who has moved to Canada and I'm going through immigration right now. It's like one of the hardest things I've ever done and every time there is a minor issue with my application I basically have panic attacks haha. It's about a year long process if you're lucky.
I guess I wish we had good information on the chances of refugees being already radicalized (or close) versus the chances of any immigrant or US citizen or visitor. Like - how big is the refugee threat statistically? I know in Paris attacks we had no refugees. In this San Bernardino attack she was not a refugee but she was indeed someone who immigrated to US successfully. (How is this fair, I've been working and worrying my butt off for months to get to permanent residency in Canada and this terrorist gets it faster than I did... grrr...)
Sometimes I do wonder if this is one of those things that just scares people more. We have mass shooters who are not connected to terrorists (any kind).... are they LESS scary than terrorists? I mean, it's pretty scary either way, right? Maybe we over estimate the amount of terrorist threat. Maybe it's similar to people who are terrified to fly in planes, but have no fear of cars, even though cars are more statistically dangerous.