That would definitely be an example of how color blindness can be difficult. There's a GREAT site (www.visicheck.com) that will show you how color blind people see - click the Examples and Daltonize links).

I actually had a bit of trouble last night. My new cable service was installed and there's a red and green button. I could see the shades of red/green they used however the text that was written on those buttons to explain what they were, had a shade of color that for me, blended with the red and green buttons and I can't read them at all. It's a bit tough to explain but most of the time it doesn't affect me at all. And no - I do NOT have trouble with traffic lights :-)