Traffic Light Coded Dog Collars

I recently came across these "traffic light" color coded collars and I think they are a really good idea. Especially for those dog owners who visit dog parks or have to walk their dog in public. I believe I would act accordingly, if I saw a dog wearing on of these collars.

http://dogspired.com/color-coded-system-for-dog-collars-and-leashes/

What do you think?