I think the big difference between the 1700s and today that seems unacknowledged in your post is that most communication happened face to face and was not documented for the government to intercept.
You and your wife could not be forced to testify against each other(Spousal privilege), but your private sms conversation absolutely could be. (What was possible as only a private conversation is now easily sent across the world, and as a consequence is sniffed and stored by potentially many parties.)
This is not a surprise for anyone who understands that they are sent in plain text, but from the context of people, those conversations would still be considered private communications between spouses.
I am not saying the law gives a shit about the distinction, but persons absolutely do. I hope you now understand the sentiment a bit more.
You and your wife could not be forced to testify against each other(Spousal privilege), but your private sms conversation absolutely could be. (What was possible as only a private conversation is now easily sent across the world, and as a consequence is sniffed and stored by potentially many parties.)
This is not a surprise for anyone who understands that they are sent in plain text, but from the context of people, those conversations would still be considered private communications between spouses.
I am not saying the law gives a shit about the distinction, but persons absolutely do. I hope you now understand the sentiment a bit more.