I got three of them at once a few years ago for downloading bleach after crunchyroll got the streaming rights for it. Nothing happened and no fucks were given.
Aren't private trackers useless anyways? I don't think there's shit you can do if you get a letter, it's all random dumb luck. I would tape that shit to my wall if I ever got a letter. It's like winning the lottery.
They're not the perfect defense, but not useless either. Only thing better is using a VPN AFAIK.
I got my internet taken away after my 3rd letter and wasn't able to get internet in my apartment for a year afterwards. We had to move and use someone else's name. Shit sucks when there is literally only one option for internet providers.