Why the ground goes down first

A lot of the scribble drawings begin as one flat colour across the whole frame. Violet, red, black. Nothing to look at yet.

That gets a decision out of the way early. The ground is already the loudest thing in the picture, so the line never has to fight for attention. It only has to hold up against a colour that is not going to move.

It also makes failing cheap. If the line is wrong on that field you can see it inside a minute.