I understand how to make bread, bakers-percentages, etc. It's just that when it comes to flour a cup is a terrible measurement, due to the way it packs and the different volume involved in various varieties/types of flour.

Most of the time when I'm cooking and I see an American recipe I just google the conversion; a cup of milk is easy to deal with. Just a minor irritation most of the time, but for some things it matters.