:) It dissipates after a while and some of it turns into liquid so if done properly you should get the "liquid amount" ordered up to the little needle mark on the glass. A different culture. Here in the UK I always get an ale that spills on my fingers when I carry it as it is 100% full...

Amount of head on lager varies from country to country but it is hard to argue with a Czech given that they invented Pilsen lager. A good head has a different taste and adds a different texture to the beer and makes the carbonation (high in a lager) more smooth and less bitter.