Interesting point but in fairness all musical instruments taken to the stage are used in low light/blackout/glare/smoke filled scenarios & I can’t think of many that are white!
Most are black with white legends, (Nord the big & very common exception), I agree that red on black isn’t ideal.
However IMO by the time most artists are stage ready I doubt they’d need to read the lettering anyway. You don’t see guitarists fervently searching for the 7th fret, it’s instinctive.