Meter Color Ranges???

It might only be that when LED meters first appeared in mix desks the only color was red and yellow, then came green and yellow but it was whatever a manufacturer put in at the time.
The newer LED color helped make it appear modern.
It sort of became green yellow and red meant overload and orange was nearly red. Slightly more gradual information.
But different manufacturers had a different look.
But there was some variances with VU meters too depending who made them. But LEDs where considered more accurate then VU meters as a VU could let an overload go by because of the throw. 
Bar graph LED meters read the peak values where VU meters because of the throw of the tiny
transducer give an indication of average loudness.