Why does it every diagram of a circuit choose that the current comes from the POSITIVE side?

I understand that they choose to believe that the positive side is positive in electron, meaning there ARE electron, and not VOID of electrons making it negative...

But physics 101 teaches electrons are NEGATIVE, making the side from which they originate over negative,, thus then flow from negative to positive,, its so easy,,

Why do engineers construct circuits the other way around? Some circuit are positive as negative and some circuits are negative as negative. Why is that so?