I have another example from work. Most if not all of the people I work with have personal boats, ATVs, etc, and so in their free time tow trailers pretty regularly. We also use trailers at work. Some college interns start working with us, and no one bothers to check their trailer knowledge because (you guessed it) it’s common sense. Which resulted in the college interns trying to drive a vehicle into the trailer when it wasn’t hitched up.

What the interns didn’t know is you want the trailer to be hitched to a vehicle so the front of the trailer stays in place when you’re putting weight on the back. Otherwise the trailer becomes a seesaw and the front end jumps up into the air.

My general rule is if you’re about to say something like, “That’s just common sense,” you should stop yourself. Common sense to whom? In my experience people call something “common sense” when it’s something they’re used to doing and they forget not everyone is used to doing it.