It costs a LOT of money to camouflage a military vehicle with paint. A HMMWV costs, IIRC, $14,000 to paint in camouflage. The paint itself is very expensive and the labor to do it is also expensive. And remember, a HMMWV isn't very big. If you were to camo paint something like a Heavy Expanded Mobility Tactical Truck, it would probably cost you $50,000. So...no one does it. If you get a new vehicle, it's painted desert camo at the factory, but your old one is going to remain green. Don't worry, though...your old one will wear out real quick in the desert and you'll get a tan one anyway. If you think THAT's bad...I went to an air show at a small airport in North Carolina. There was an MV-22 Osprey there, so I started talking to the crew chief. The Marines had one Osprey camouflaged and paid a million dollars to do it. Now, as to uniforms: The current "Army Combat Uniform" or "Advanced Combat Uniform"--it has been called both--is designed for use in desert, woodland and arctic environments using the same pattern and colors for all three. Units are trained to operate in specific theaters. There are three basic camouflage schemes in use in the military, forest, desert and winter. Changing from one scheme to another takes time and effort. Soldiers and Marines are issued a set of uniforms at basic training, typically forest, since that is the area their training is conducted in. After that point they are responsible for their own uniforms, and receive a stipend to assist them. It takes time to acquire a new set when the scheme is changed.