I read in a book on Industrial Light and Magic that, back in the days when SFX were done frequently using mat paintings, that they didn't have trouble finding artists who could paint everyday life realistically (most art graduates could) they had trouble finding people who could paint things that didn't actually exist and make them look real. One of their final tests for job applicants was to take a scene description from something cut out of the Empire Strikes Back (something not filmed) and have them paint it as if it were a photograph given art direction, a basic layout, and lighting and camera lens specifications. Very, very few people passed this test.
It's a lost art these days.
It's a lost art these days.