The story of the TRS-80 silver color is funny, seen in retrospective. Other colors would have been simply to expensive for Radio Shack. So, in this case silver shouts "CHEAP" - really!

On the History of Computers one can read:

The monitor was a modified black-and-white TV built for Radio Shack by RCA. When RCA told Radio Shack that the TV case’s standard color was “Mercedes silver”, and any other color would cost extra, Radio Shack accepted Mercedes silver and painted the rest of the computer to match the TV. When you use a Radio Shack computer, you’re supposed to feel as if you’re driving a Mercedes; but since Mercedes silver looked like gray, Radio Shack became nicknamed “the great gray monster”. Californians preferred Apples, whose beige matched their living-room decors. (Later, in 1982, Radio Shack wised up and switched from “Mercedes silver” to white.)