The diesel fuel pump in one state is green, while in another is black. Quite confusing for the traveler.

One may find oneself confused as to why the pump does not fit into your gas tank…however the prevention of error is extremely important in this case.

Consistency and standards are good things. While making something obvious is the best approach to software design, respecting standards prevents confusion against learned behaviors.

At the same time, preventing error is equally vital, especially if the error will cause serious, irreparable problems.