Schools do it - they say "Paint this" or "Paint that". The child looks around and sees what his/her peers are doing and tries to copy that. Part of trying to fit in.
A friend of mine who was a primary school teacher (elementary school in the US?) said that the way that she tried to get around that was to make them paint on their own, unable to see what the others were doing. Forced them back on to their own imaginations, so to speak. But by year 2, they conform anyway. Kids' opinions of other kids have an amazing effect on what they do!
My sister, who is a kindergarten teacher/zookeeper, has some really, really funny stories about kindergarten kids, art, their parents and the interactions between them all. But they are not suitable for the delicate ears of the general populace of the Board.