These technologies give privacy and anonymity under normal conditions, but they do not prevent anyone from logging ciphertexts. If someone has logged ciphertext, and the government subponies someone to divulge their private key and subponies whoever has the ciphertext, those ciphertexts as good as plain text.
I mean, I don’t think anyone really expects that encrypted messages are necessarily secure in context of stolen private keys. I assume that a lot of encrypted traffic is either recorded at the ISP/backbone level or at least can be on demand.
