I work for a printing company.
Think of this - why everything is printed mostly in black ink? why not navy blue, or dark hunter green?
Because black is a stock color.
The manufacturer stocks it, and usuesuses it left and right. Most other colors have to be a special order - this comes with increased costs, lead times and paint expiration. If you did not use all of it, paint does expire.
To the printer-happy community let me remind you that painting a jet is not like priningprinting a page where three base inks are used to create a perseptionperception of color. Paint of any color has to be manufactured separately.
So I think that from a manufacturing stand pointstandpoint it is just so much cheaper to use stock white paint.