At least in my country, there has been serious laws protecting the users from police opening letters (1962:700; Postlagens tystnadsplikt). This was changed in January 2023 because people exploited it to send drugs thru post office [1].
Of course without any protests in Sweden because again people don't realize their rights to privacy are taken away from them.
1: https://www.svenskhandel.se/nyheter/nyhet/lagandring-ger-moj...
This is the source of some massive disconnects between people and their governments, I think. They had some permission, which we basically agreed on as a society, when their tampering was obvious and/or limited in scale (just due to practical constraints). We gave our consent to be governed with those constraints in mind.
Nowadays they are continuing without those implicit constraints and they don’t want to have the conversation about implementing new explicit constraints. This isn’t the deal we agreed to, really, it is just what they can get away with without permission. You can rule over a populace without their permission, of course—it’s just very different from the sort of pleasant (albeit never perfect) relationship that willing populations and their elected officials have had recently.
1: https://commons.m.wikimedia.org/wiki/File:Rational_harm_asse...
Yet I can go to certain neighborhoods in Stockholm and get pretty much every thing under the sun and that's open 24/7.