Recently I noticed some people having extreme problems with some very simple and well know user interfaces:
1. Elevator in a train station. A woman touched the sign for up but not the button and was confused that nothing happened.
2. Door with standard door handle in another train station. A man was completely confused that the door didn’t open automatically and needed some time to figure out how to open the door.
And those people are supposed to operate something more complex like a computer?