My view is :-
This is Wartime.
Why bother repainting a vehicle a slightly different shade of green? Waste of manpower and resources. I have seen Jeeps with black camo, but most seem the standard Olive Green. Jeeps were only supposed to last 3 months, so why a respray? Post war I can understand a respray to clean it up after a base overhaul - is this where the confusion is?
If the vehicle had to have mods (eg a Firefly) then it would need painting, so a respray is understandable.