the price of freedom: infinity times a lot of something?

Why are some non-government humans happy (or at least OK) with government humans spying on them in spite of the absence of evidence of terrorism prevention by such means? Even if the government prevented say, 50 deaths a year (as far as anybody knows, it doesn't!), the return on investment would be miniscule in comparison to the return on other ways of spending money (and freedom!), or not taxing. "TERRORISM!" -- not the thing itself but the word and what it invokes -- is scarier for some than a million traffic accidents covered in spiders, because "1 terrorism" > "1 spider-covered traffic accident". By how much? Infinity, approximately. Math doesn't matter here. There's a term for this: scope neglect. It's only part of the answer, but worth mentioning.