actually, the law leaves remarkably little room for interpretation in this case.
here's the law in full, emphasis mine:
Strafgesetzbuch (StGB)
§ 202a Ausspähen von Daten
(1) Wer unbefugt sich oder einem anderen Zugang zu Daten, die nicht für ihn bestimmt und die gegen unberechtigten Zugang besonders gesichert sind, unter Überwindung der Zugangssicherung verschafft, wird mit Freiheitsstrafe bis zu drei Jahren oder mit Geldstrafe bestraft.
(2) Daten im Sinne des Absatzes 1 sind nur solche, die elektronisch, magnetisch oder sonst nicht unmittelbar wahrnehmbar gespeichert sind oder übermittelt werden.
the text is crystal clear, that security measures need to be "overcome" in order for a crime to have been committed.
it is also obvious that cleartext passwords are NOT a "security measure" in any sense of the word, but especially in this case, where the law specifically says that the data in question has to have been "specially secured". this was not the case, as evident by the fact that the defendant had easy access to the data in question.
this is blatant misuse of the law.
the data law makes no attempt to take into account the intent of the person, quite differently from when it comes to physical theft, which is immediately and obviously ridiculous.
you mentioned snooping around in a strangers car, and that's a good comparison!
you know what you definitely couldn't be charged with in the example you gave? breaking and entering!
because breaking and entering requires (in germany at least) that you gained access through illegal means (i.e.: literally broke in, as opposed to finding the key already in the lock).
but that's essentially what is happening in this case, and that is what's wrong with this case!
most people agree he shouldn't have tried to enter the PW.
what has large parts of the professional IT world up in arms is the way the law was applied, not that there was a violation of the law. (though most in IT, like i am, think this sort of "hacking" shouldn't be punishable, if it is solely for the purpose of finding and reporting vulnerabilities, which makes a lot of sense)