why would pens perform different for right vs left? they're asymmetrical

In left to right languages lefties are draging their hand across what they just wrote and so need something that dries fast or it smudges. I suppose right handed hebrew writers would have the same issue (are their other bidirectional languages? )

Arabic, Persian.

The whole language is against you. Writing with your left means you can smear everything unless you do some odd maneuvering with your wrist.

Mostly because of smearing and the direction of writing: left-hand writers "push" the pen more, while right-hand writers are "pulling" the pen more (not totally and not 100%)