Shouldn't change when you get closer either, airless planets are eroded, granular and dusty they tend not to be made of solid blocks of material to have masses of colour variety. Tend to be sand of one colour and rocks of another, sound familiar? Have you looked at surface shots of Mars?
There are planets that exibit colour variance in game at that kind of level but they are rare, just like in real life.
Odd that you chose to point out that something would look a certain way "from thousands of KM away" when you really meant to say it would look the same at any distance. Assuming that's actually what you meant from the start? I guess what I'm saying is that from thousands of KM away*, it looks like you're talking nonsense.
* by which I mean "from any vantage point at any distance"