Welcome to the land of the free, etc, etc. Here in the US, there are strict weights and measures rules about things that are required to be weighed or measured, but that is a specific list of items – gasoline, items priced specifically by weight (like meat), packaged liquids in marked containers (like milk) – and lots of stuff isn’t on the list, and draught (or as we bastardize it: draft) beer is one.
Every bar can use whatever glasses they want to and also to pour however they want. In el cheapo chain restaurants like Applebees, I’m pretty sure they don’t even train their bar staff (which most typically is just the wait staff, not actual trained bartenders) on how to pour, so you wouldn’t get consistency from beer to beer.
