AFAIK, what this dude did - running a script which tries every password and actually accessing personal data of other people – is illegal in Germany. The reasoning is, just because a door of a car which is not yours is open you have no right to sit inside and start the motor. Even if you just want to honk the horn to inform the guy that he has left the door open.
https://www.nilsbecker.de/rechtliche-grauzonen-fuer-ethische...