Avoiding authorities isn’t the reason to join private trackers. The main reason is access to all the media you could imagine. And even can’t imagine sometimes. That obscure, foreign, made for TV movie from 40 years ago? Coin toss it’s available on private trackers. But it’ll be nowhere on any public tracker. That’s why when OP asks what do you do when you can’t find _____.torrent, my answer is go private. It’s likely they’ll find it there.