Re house - the reason why people (not just kids) will draw the same symbolically looking house is due to the question itself: they want you to recognize the house in what they've drawn. No one wants to fail, everyone wants to please, and it's the same with llms.

If instead you ask to draw some fancy interestingly looking house you'll get more variety - now the task is not to have the question giver recognize the house in their drawing, but to show how they imagine fancy or interesting house.