That does exist, it's called semantic highlighting.

In any case, my analogy was not perfect, but neither was Russ's! The point is it's totally normal and not "childish" to use colours to help distinguish things. Traffic lights do not technically need colours (you can use the position of the lights - I assume that's what badly colourblind people do). Nor do transit maps technically need colours - you could just label the lines, or use patterns.

https://www.flickr.com/photos/gywst/1407078279

It's completely absurd to say that colours are childish because they can help children.