How do these things happen?

You think that we are surrounded by autoactivated control systems and surveillance mechanisms to prevent mistakes like this to ever occur, but oh no, rest assured, if we leave th human brain behind shit is going to hit the fan.

This is an elevator note @ Heliosgatan 41 in Stockholm. It says:

If you are going to floor:
6: press 7
5: press 6
4: press 5
3: press 4
2: press 3
0+: press 2