I think most people associate the term “kid-friendly” with bright colors. A kid-friendly party would have a clown in a neon costume. A kid-friendly park would have some kind of large climbing apparatus painted in blinding primary colors.
To me, however, kid-friendly is the color white. As in a white flag. As in “I surrender.” The most kid-friendly item in our house is, of course, the TV; when a kid is in front of it watching a show with say, a bright purple dinosaur, it’s a reminder of the fact that I’ve simply given up for half an hour.