I’m not sure how real companies handle this, but I can share what we did in a student organization at my university that provided internet to its members.

Not only could we monitor who was downloading a lot of data, but we also received emails from legal organizations informing us that a specific IP in our network(All members had a public IP) had downloaded copyrighted content. They would ask us to disconnect that user. These emails typically came with an XML file attached, filled with legal information and details about the content being downloaded, often including the exact torrent filename.

We built a system that would automatically parse the XML and forward the email to the user responsible. The subject line may or may not have been “Use a VPN, you idiot!” at some point.

We also maintained a “high score” list to track what was trending. The last time I checked, Rick and Morty was in the top 3, but that was a while ago.