Error Prone

Yes; People are prone to make mistakes.
I think it's time we disabuse ourselves of the idea that any system that involves human decision making will be error-free. Check this out:
Tug Grounded on Bligh Reef in Prince William Sound
Now, tugboat Pathfinder's exact and only job is to ensure the safety of oil tankers like Exxon Valdez as they transit Prince William Sound and pass by the reef. The tug is designed for the job, the crew is trained for the job, the crew is experienced and has local knowledge of the area. Indeed, since the Exxon Valdez Disaster in 1989, Bligh Reef has become perhaps the most carefully watched hazard to navigation in all of North America. Pathfinder didn't just graze the reef either; it slammed square into it.
What happened?
The Coast Guard is investigating. Well, I should hope so!
One is inclined to suspect Human Error is at the heart of this.
Consider: If a highly skilled experienced crew going about their work can screw up this badly.
How can one reasonably expect that the drones who toil in the 'Security' Lines at airports will unerringly identify the crazies who want to board a plane with a condom full of firestarter? Out of the Billion plus people who pass through the lines each year?
Isn't this just a bit of an Unrealistic Expectation?
Meanwhile, you can follow the track of the Tug Pathfinder here.