Human nature. Stanley Milgram showed this in his famous experiment:

http://en.wikipedia.org/wiki/Milgram_experiment

It is also exceedingly difficult to resist group pressure, to think for oneself and to stand up for what you believe in. These actions often lead to ostracism by the group, which may mock or even turn viciously on the outlier, who exposes their weaknesses/misconduct.

Standing up for what you think is right leads to punishment - in this case, a potential delay in flying or an inability to reach your destination at all [see: ocean for anyone who wishes to pipe up with 'flying is not a right'].