In the early 1980's I worked at a company that sold its products all round the world. Parts of the hardware and software had to be reworked for different countries, but to some extent we tried to follow Swiss standards everywhere for signal emissions and use of colors, for they were the toughest in the world at that time. The color standard is deceptively simple: Green for information, yellow for warning, red for danger. Now how do you apply these colors to computer products?
Here's a simple case: A light on the disk drive blinks on when data is written to the drive. What color should it be? If the drive is removable; if it's say, a floppy drive, then make the light red, because you'll lose data if you pull it out while the light's on. For a fixed drive, make the light green, it's just information. (We used to argue over this kind of stuff for days.)
I drove a full-size rental car for ten days, and I REALLY thought about those standards. This car is full of displays that you can modify and set with options. One of them is whether to display your speed in mph or kph. There's no danger of forgetting which you've chosen, because the car displays these units on the dashboard ALL THE TIME, in RED! While driving, my eyes strayed to that bit of red every two minutes. Red means danger, after all.
If you ask me, the mph display should be green, except that it would be neat to change it to yellow above, say, 55. And change the kph from green to yellow above 100. And give me a display where I can change that boundary speed for the color change. (How parameterized should a car be? I think there should be so many settings to review that a twenty minute traffic jam's not boring.)