The service people basically get 10% of anything that they sell. So it's quite a lucrative earner. The actual wage they get is pretty low though. However most of these people actually take 2 weeks out of their holidays from whatever job they normally do to work at the Wiesn, so it must be well worthwhile.
As regards tipping, if you tip well, at least at the start, then you will get decent service for the rest of the evening. They do remember. If you don't tip then you might find that your assigned waitress is suddenly very busy whenever you're looking for another beer. It's well worth dropping the extra bit of cash to be sure of getting looked after.


