It isn’t the ISPs that send those letters, it is overseas privacy lawyer companies that send the letter to ISP, and they relay it to you.
All the letter ask of the ISP is to communicate with end user and ask them not to-do it, and then the ISP can reply on that letter that action has been taken.
I only once ever got a warning for torrenting. I was in University at the time circa 2016. The first time was just a warning but they take disciplinary action if you repeat the offence.
The key for the first time is to more or less admit you did it and then say you won't do it again. Apparently people who tried to lie and argue with the IT guys ended up getting punished.
Remember the days of having a 3Gig cap on 512k ADSL so you have a spreadsheet of 100s of adsl accounts to cycle through and downloading from ninjacentral