You’re confusing „ohne Alkohol“/0.0% beer with „alkoholfrei“/“non-alcoholic” beer.

In Germany, drinks only have to be labeled as alcoholic from 1.2% upwards, so

• unlabeled fruit juice may have up to 1.2% (has more likely 0.3% or so)
• alkoholfrei may have up to 0.5%
• 0,0 may have 0,0% (rounded down from up to 0,04999…%)

https://de.wikipedia.org/wiki/Alkoholfrei