there are but it is very rare and comes with drastically limited eye sight anyways.

Red/Green confusion is quite common though, there are estimates of up to 8% of ("western") males. Definitely a number to consider if you want your whatever to cater as many people on the market as possible.

The commoner kinds of red/green colorblindness, though, are by no means absolute. Most red/green colorblind men can tell highly saturated reds and greens apart -- they only have difficulty with low-saturation refs and greens.

> there are but it is very rare and comes with drastically limited eye sight anyways.

As one of those very rare individuals you allude to (see everything in greyscale), you should be aware that my eyesight (and many people with a similar condition to me) is "limited" but not to the point where i can't cross the street or need to use a screen reader.

Having said that, even for me knowing the colour would be useful even if I can't exactly distinguish it (e.g. I'm waiting for a white station wagon, its definitely not that black hatchback that slowed down in front of me)