Earlier quoted context omitted.
You pick the law of one of the weakest privacy jurisdictions and argue that Slack should standardize privacy on most invasive level this country's law allows. What is this declaration of rights for corporate eavesdropping?
Why do you feel the need to defend Slack? It was their decision to do this to ensure they wouldn’t be forced out of the corporate market ($$$$$) and, I hate to break it to you, US and EU law are very similar in this regard. Corporations in the EU can listen to your business correspondence just as easily as US ones, and in neither do you have any real expectation of privacy at work.
I'm defending employee rights and generally the human right to privacy against arbitrary surveillance, not Slack.
(1) https://www.helpnetsecurity.com/2017/09/06/workplace-surveil...