That is flat out untrue. I actually was surprised how easy it was to get prepaid SIM cards (just buy them at any shop/gas station, no info/ID required), load and use them however and whenever I want (also 15 Euros for 5GB 3G and works in USB data sticks, pretty nice).
Illegal to have open Wifi, that is true :-) (I think it's a 125 Euro fine)
By law, they have to request your name, adress and DOB before you can activate the card (usually not done in store, but online at home). They don't need to validate them though (no ID required) and it's not illegal to make false statements :).
No, it is not illegal per se to have an open Wifi, but there is the dreaded paragraph of "Mitstörerhaftung" - that means in lots of cases if someone does something illegal over your open Wifi (say copyright violation), the person who runs the open Wifi will be liable for it.
But in general, yes, it's purely a matter of civil law.
[1] http://www.gesetze-im-internet.de/englisch_bgb/englisch_bgb....
The service providers offering anonymous SIM cards operate mostly on o2/BASE network which have very scarce coverage, only some of them use Vodafone network (better coverage), and I'm not aware of any operating on TMobile network. If you want to buy a SIM card directly from network operator (o2, Vodafone, TMobile) prepare your passport/id and document confirming your address.
I'm really tired of this smug German "privacy is very important for us" bullshit - because no, it isn't.
slowmotion made assertions about germany's legal requirements, not the corporate policy of specific ISPs.
Aldi Talk. Coverage is good, speed is okay. 4G is supported in the main cities.
Delivery is only possible within Germany, but you can grab the SIM card at any Aldi for 12.99€ including 10€ credit. Top up with a 5€ voucher brought at Aldi (ask at the register).
An increase in the certainty of the data source is also damaging to privacy.