You misunderstood. It's not about punishing people who USE open Wifi networks.
It's about a woman who downloaded pirated music, claimed "Oh, somebody must have used my open Wifi", and got told by the judge that she gets at least part of the blame for the pirating.
USING open proxies etc. is legal in Germany, too - but if somebody does something illegal using such a proxy, the owner of the proxy can get serious trouble... hardly news for proxy operators, of course, but the new twist here was that the judge ruled that neglecting standard security precautions (encrypting the Wifi) is not a viable excuse anymore, as EVERY Internet user can be expected to learn how to use his equipment or to pay somebody to properly install it.
Logical next step would be to punish all the people who run zombies :-)
Juergen Nieveler