Three men go on a camping trip. On the way there they're told by a park ranger to be careful because their campsite is located near some dangerous animals. What dangerous animals? The park ranger won't say, because that would be profiling. "Just keep in mind", he tells them, "that people who camped there in the past never made it back alive."
As the sun goes down, they pick up their hunting rifles and stand watch for dangerous animals. But they don't know what dangerous animals, they're watching out for. And they don't want to profile. So they keep watch for crickets as much as for bears, and for deer as much as for mountain lions. A rabbit, an owl or a bullfrog all equally frighten them out of their wits. They open fire on mosquitoes and stand watch against monstrous raccoons. By the end of the night, they can hardly see anything or react to danger. That morning, a pair of mountain lions stroll lazily into their camp and find them snoring away.
This little story illustrates why we can't do things this way. Because it's stupid and it's suicidal. Human survival is based on recognizing threats, not on reacting to all stimuli because one of them might be threatening, but we don't want to single it out and make it feel bad. If we actually did things that way, we'd all be dead by now.