This is true, but AI can be used as a tool to summarize and otherwise distill a massive amount of information to a form that someone can make sense of. It was probably cost prohibative to go through this data before or making specific snooping tools.
If your company uses the Microsoft ecosystem, have a look at the search function in Delve or SharePoint or whatever the fuck they're calling the shared employee document repository this week.
At one point, I don't know if you still can, the search would scan meeting transcriptions if the organizer fucked up the privacy settings.
I searched for naughty bigboy words and came across a transcript of two employees (who had since left the company) just absolutely shittalking a manager.
Besides some hilarious typos I also found some old chat logs where I was using some colourful language. Deleted that. Hopefully it's proper gone and HR won't find it.