“Zero chance” is bullshit, they could easily join a private tracker and look for IPs, they just don’t currently because private trackers are not widely known.
One site on that list, for example, TorrentLeech.org has been around for almost 18 years and has hundreds of thousands of active users. In fifteen years I’ve never had an issue.
There are also foreign language trackers that are largely immune like rutracker.org - you just have to make sure to download the English versions
so of course i didn't use it enough and was banned for inactivity
The risk and effort is probably not worth the reward, considering how many public tracker users are there.
What I'm imagining: someone who is mildly connected to execs at various studios/labels starting a company that participates in private trackers, and then passes information about infringement/infringers onto studios. They would only need one or two studios as clients to prove the concept and (informally) prove the idea to the rest of the industry. Their agreement with client studios includes an agreement that they won't be sued for infringement that occurs in the process of finding (other) infringers, doesn't include any license to works, and certainly doesn't include the ability to sublicense!
Sure it's possible that when this eventually goes to court, a chain of "activist" judges might go against the status quo of a company taking steps to protect its "property" - discard corporate veils, call the investigator's uploading an implicit sublicense, etc. It's just not likely, and the failure mode still would be individual licenses for the specific downloaders that were in the swarm at the time, not blanket rights to redistribute indefinitely.
Most good private trackers have an invite system, you can't just join one on a whim and get access.
Their process is profitable enough just by scanning the well known ones so they don't need to bother with trying to get access to private trackers.