> A "backdoor" implies a secret (to both user and provider) extraction of the data. Now, a judicially authorized/vetted extraction of data of a specific customer/timeframe is a different thing (even better, make it forward/backward secret). Sure, it is alarming and certainly ethically debatable. But it is not "a backdoor"
I don't see what you mean. The first one is much easier than the second one (and the second one does not need to be implemented like the first one).
Remember, if you have access to the server or the end client you can do either one. That's why the legality supersedes the technology, because the technology is not perfect.
And how do you implement one without the other?