/ic/ - Artwork/Critique

What makes it obvious when an anime/manga illustration was created by a westerner?
I'd like to ignore coloring and shading for now.

My art teacher (western herself) said it's all in the lineart. I don't quite understand though.
Is the feature placement better? Does asian manga/anime make the volume of a body look more feasible?
I don't get it.

What are your thoughts?

Why do western artist have so much trouble emulating the Japanese art styles? How come western fanartists that have been drawing nothing but anime fanart still struggle, yet many Japanese beginners nail these styles with seeming ease.

And how is it possible we can detect almost immediately if a piece of artwork is done by a westerner simply by looking at it, yet it's so hard to pinpoint the exact aspect that exposes the fact.

This is a serious mystery that has been bothering me for a long time.