(Just for clarification, this doesn't make it any better or less traumatizing. It is probably much more traumatizing, people just have to cope with it, because you can't live in constant fear forever.)
I have friend who in Jerusalem Israel during the second intifada. Terrorists were blowing themselves up on busses killing or maiming nearly everyone on the bus. Yet the locals continued to take busses because they needed to get to school or work and stopping normal life until after the terrorism stopped was out of the question. Not everyone can simply go on a vacation until everything fixes itself.
Reminds me of a half-jokey comment I saw a few times after one of the more recent London attacks: Non-Londoners were desperately avoiding central London; Londoners were complaining the Tube was delayed.