What is it that they see that scares them? Well that's a good question. What scares you? While you are standing in line they do a brain scan of everyone, then they have the people who are scared of the same thing go through together (that is why you see various groups of people who don't look related, same sex, etc)
Then they provide for those people the EXACT thing that they are most afraid of. So for a lot of people it's Public Speaking. The lights come on and they are in front of a crowd and a direct says, 'You're on! 20,000 people want you to talk! Now!"
For a lot of people it is being hit by a car. Those are the easy photos to get and they are mostly shown here. But some of the others give you a much more existential fear. So for example, for a number of Right Wing Republicans' It's a Black Liberal President who is going to take their guns. They have a person dressed up as Obama jump out and say, "I'm coming for your guns, and white women! I'm going to make you buy health insurance!"
For Progressives it's, a guy dressed up like Dick Cheney jumps out at you holding his old heart in his hand and saying, "I'm never leaving! I'm still running the Government! I'm going to take away MORE of your rights! Sarah Palin for President!"
And if any .01 % ever attended (they don't) They have a woman dressed up like Elisabeth Warren jump out, "I'm going to make you pay Eisenhower rate taxes! And take big money out of campaign finances.