Torrents are registered. Only people who can access the private website get access to the torrent. It’s much harder for the bottom barrel legal teams that just sit on them recording IPs, like they do on public ones.
They can certainly get into a private tracker but will be found before long. This also depends on how the private tracker is run and by whom.
Use a VPN when doing illegal shit. Don't leave to a shady website.
The 9th circuit court judges really have no fucking clue about technology do they