This question Is there a color code for notes? includes a few standards for colouring notes, to make it easier and faster for our brains to tell the difference between notes.
For example: C = blue, D = green, E = yellow, etc.
This would obviously help children learn to sight read faster, and increase the speed at which they can sight read thereafter. In fact, it seems unlikely it won't help adults - even experienced musicians.
Once a standard is settled on, some instruments can adopt the colours too, e.g.: learner piano keyboards can colour their keys.
Historically colour hasn't been practical for all paper sheet music. But paper sheet music is slowly dying, to be replaced sooner or later with digital displays (tablets, etc).
But I'm not seeing colour being used like this much yet.
Is it just us old musicians underestimating how important this would be to young musicians? Or is there some actual reason not to colour code all notes in digital sheet music?