When you draw a tree, you mistake one side for a single
The bias of easy drawing
When you write (Christmas) tree, one side of the tree is mistaken for single.
Draw a pyramid and you'll think the bottom is bigger.
---
This page is auto-translated from /nishio/ツリーを描くと片側が単一と勘違いする using DeepL. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I'm very happy to spread my thought to non-Japanese readers.