I think he wanted to highlight that the amount of a "standard" glass size highly varies depending on your locations.

When you're drinking in cologne, you'll usually get 0.2.

When you're drinking in Berlin, you'll usually get 0.3-0.33

When you're drinking in the South, you'll usually get 0.5 in a normal restaurant and 1 on a beerfest or even beer gardens.

Not standard but you can order it in many restaurants in southern Germany. Its called “Mass”. Standard would be 0.5 in most occations, however there are some festivals where 1 Liter is considered as standard. Especially if you plan to drink a lot you’ll just order 1 Liter beers.