The United States District Court for the District of Utah was the first Federal court to adopt the doctrine of vicarious consent and did so in the context of custody proceedings where one parent recorded the other parent's conversations with the couple's two minor children, then three and five years of age.
However a statutory construction waives no 4th amend privacy nor a 5th amend privilege. Both are inviolable protections of the Supreme Law and not subject to interpretation that would impair or abridge the citizen.
True the minor is unable to grant consent and the parent has a duty to protect. But the issue is that unless the other adult who is the real target of the invasion of privacy expressly consents. The law is being broken. It's no different than an illegal search and seizure violation. Or a breach of "client confidentiality".
Even further can a drunk date give secret consent for sex. Implied consent is not consent at all. Nor can anyone be forced to give open or secret (virtual) permission to violate or abuse another. Consent must be mutual and express for it to survive any test or objection.
These common law principles (in our Bill of Rights), derive from the Magna Carta (The Great Charter) 1215 enacted to protect fundamental human rights from oppressive arbitrary abuses.
Secret consent is a paradox. How would one secretly give "vicarious consent"? And why would any reasonable educated person who expects to enjoy privacy allow and or endorse such a trespass? It's clearly a perversion of law and clearly incompatible with our free society.