Tor exit nodes don't have any information to identify the end user. They don't know who it is, so there is nothing to subpoena or turn over. Subjecting low-resource entities to a known-futile legal process is a form of harassment.
Exactly: They intentionally built their transit system without cameras. Who benefits from that, except criminals? Oh yeah, sure: North Korean dissidents, Saudi LGBTQ people, etc, etc.
Yes, quite noble. But: How many of those are there using it, and how many criminals? It's mind-boggling how people so adamantly insist on seeing this only as black-and-white, and refuse to admit that there even exists something to weigh against each other.
It's not known-futile. A misconfigured Tor node could be storing all sorts of useful traffic data. Besides, there's also the possibility that the exit node operator themselves could be the actor; since the trail stops at them, they're under suspicion.
Camera feeds, ticket records... All of that is accessible via warrant. That's probably the most salient example in this context.