PAA: What all of those basically come down to is what people FEEL, not what’s actually true. Worry makes sense on a visceral level, but it doesn’t on a logical one. While the OP’s parents don’t need my permission to make this decision on a visceral level, I’m simply pointing out that if she wants to make a case, there is plenty of material for her.
Just an addendum about one of your points- yes, people do get used to the rockets. I was in camp with several Israeli girls who (obviously) kept in constant contact with their families in rocket-prone areas in Israel. Hearing about the constancy of the rockets in such a casual way both kind of freaked me out and helped me see the whole thing as less of a big deal. While you’re right that the panic of the situation is hard, seeing how so many people are simply living normal lives- the same way that iyH I will be in sem- helped me realize that I had to start seeing these things a different way. Of course, a situation where rocket attacks are so routine that people are immune is a sick and twisted one, but the point still stands.
I do, however, agree with your point about the panic and fear of the unknown. People do not dwell on whether there will be a car accident at any given moment, while they do have specific moments- like sirens- in which there is a fear. At the end of the day, though, the material risk is quite low.