Also, recently, FBI "hacked" in to Exchange servers that were vulnerable (with court authorization) to patch them [1], so it does happen. But I agree with your sentiment that it doesn't happen as often as it should.

The public perception seems to be that the US doesn't spend enough resources to harden its and its people's defenses than it does to surveil people.

[1]: https://techcrunch.com/2021/04/13/fbi-launches-operation-to-...