You must have missed the Shermans in the last FSO. Default terrain tile set (couple custom airfields) and they blended right in to the background clutter.
The main problem is the German armor all use a desert camo scheme as the default skin. A lot of people turn off skins for everyone but themselves on their FE, so Tigers and Panzers stick out like a sore thumb in our Western Europe terrain. The American GVs all use a dark green as the default which is hard to make out against the terrain, especially wooded areas. Additionally, if you turn down ground detail range the background clutter disappears entirely but you can STILL see the tanks. You may not know if there's clutter in the way that will prevent taking a shot, but you'll still see them.
Also, it's been discussed in another thread that camouflage on aircraft really only mattered if the plane is on the ground and not moving, or if an enemy was looking around from a good couple thousand feet overhead and not focusing their attention.
The only real fix that works for the Mains is to set the German armor to use a skin of the same dark green as the Shermans, if there is one, and to fix ground vis range so that GVs are visible at the same range as ground clutter. There's no need to fix anything for aircraft. In fact, it's been argued that aircraft camouflage works BETTER than it should.