This seems a bit analogous to the treatment of attorney-client privilege (at least in the US.) If I have a discussion with my attorney in my house, or in my att

This seems a bit analogous to the treatment of attorney-client privilege (at least in the US.) If I have a discussion with my attorney in my house, or in my attorney's office, with no one else there, the conversation is generally privileged. If I have that conversation in the presence of a third party, the conversation is no longer privileged. So, if I'm in someone else's house, I may have implicitly consented to the fact that I don't control the environment and can no longer assume the same level of privacy. (IANAL, YMMV, etc.)