People are not rational actors. There are lots of factors involved.

- Lots of people default to routines. Need to evacuate a building? Most will take the same route as they got in.

- Our brains don't jump into the flee reflex until the last moment. Although that can be a good thing, as most will act rationally first, but a little too slow then they should.

You need to prime your brains by training. People who are used to thinking and acting quickly, be in sports of work, have an edge on this. Getting into a realistic evacuation drill on a plane is hard. But you can run the steps you need to take to evacuate the plane, front or backside, in your head.