The government could tap phone lines willy-nilly until 1967[1], regardless of whether any third-party's ability to listen to a conversation.
Plus, the fact that any non-government person could surreptitiously record a conversation, and that recording be useable in court, didn't substantially change until this century, and even today it's mostly a mishmash of state laws preventing such disclosures, those laws are inconsistent, and in some states there's still effectively little preventing that from occurring. And the ability of the government to leverage third-parties to get around 4th Amendment precedent is still in flux.
All-in-all, I would think the ability, and knowledge of the ability, to record a phone call was entirely irrelevant and uninteresting in the 1940s, at least regarding people's expectations of privacy. But I'm curious if there's evidence to the contrary.
We know that now because information is available at our fingertips and we’re nerds. The average person doesn’t know that.
At the time, AT&T’s marketing was all about trust, a mission ethos to serve humanity, etc. They also had a close relationship with government at all levels. Their goal was to avoid awkward questions.
Plus, the fact that any non-government person could surreptitiously record a conversation, and that recording be useable in court, didn't substantially change until this century, and even today it's mostly a mishmash of state laws preventing such disclosures, those laws are inconsistent, and in some states there's still effectively little preventing that from occurring. And the ability of the government to leverage third-parties to get around 4th Amendment precedent is still in flux.
All-in-all, I would think the ability, and knowledge of the ability, to record a phone call was entirely irrelevant and uninteresting in the 1940s, at least regarding people's expectations of privacy. But I'm curious if there's evidence to the contrary.
[1] https://en.wikipedia.org/wiki/Katz_v._United_States