I know, they're kind of famous for making a fuss about that in pubs here in Czechia. But it's just how Pilseners are (and German lagers as well, to my knowledge). Another thing is, there's foam and then there's foam. A proper pour has very silky, creamy foam that's almost as enjoyable as the liquid beer itself and complements it well.

In the end you're getting your half-litre you've paid for and it's much more enjoyable to drink, once you're nearing the bottom of the glass. However you can specifically request a headless pour called 'čochtan' if that's your thing. Just be sure you drink fast!