I think the red light, yellow light, green light system could be beneficial for kids to learn the nutritional value in foods.
I have 4 teens and I know so many of their friends just don't have a good understanding of nutrition. Many have learned incorrect things from their parents like carbs = bad. Or fruit is as bad as ice cream.
My DS's best friend comes from a family where neither parent can cook at all. If it's not something that can be dumped into a pot or warmed in the microwave, they can't do it. My son taught him how easy it was to make a grilled cheese and it blew his mind. The 3 kids eat out for every meal unless they are eating at a friend's house. Yes, the parents have money and they aren't eating at like Applebees or whatever each night, but food at restaurants still has tons of salt. I know this because I worked in restaurants for years in HS and college.