If someone is a high value target, LE needs a warrant to bug their homes and to listen to their conversation, which implies they should have some indication of

If someone is a high value target, LE needs a warrant to bug their homes and to listen to their conversation, which implies they should have some indication of a wrong doing after which a judge grants them a warrant. With digital communications being non encrypted, it could increasingly be used for just surveillance in the name of national security, and as a way of finding out who is indulging in a crime vs just getting more evidences to prove that someone has committed a crime. If the same physical system were to work in a digital age, a company could share a special encryption key with LE for the collecting evidence part provided they get a legit warrant for that. Physical security was never perfect, but we aspired it to be as close to perfect as we could. Same applies to digital as well.