Two things:

(1) Designing icons that work for a product that's used by billions is really hard. you have to deal not just with how it looks, but how people will see it across different languages, disciplines, experience, and so on. It's practically impossible to do it "right" and to satisfy everyone.

(2) I bet you given #1, the idea here isn't to design an icon that works, but to create a placeholder for a position in the UI, and then train you to click in that general direction. That's why two icons are on the opposite ends of the navigation bar. They know those two are confusing, but they just want you to remember (<- go this way to do X, and go -> that way to do Y).