Ha genius, you can see the barman there is making a fortune.
The scam at the Oktoberfest is to fill beers below the 1l line.
The reason is thus, you don't work on the amount of kegs sold, but the weight of beer sold.
Thing is a 1 liter mass has a unit price. If you can consistently pour under the line the money starts to add up pretty fast.
I remember being involved in this fiddle when I worked in Germany and we were raking it in, I was never the instigator, but when you work in a team and don't play along things get very frosty, very fast, but you can walk away with a few hundred a night, no issue.
The guys always used to reference the Oktoberfest and how they make the real cash at the same scam.