Those are all things with extremely broad purposes, used by nearly everyone. Whereas Tor is incredibly niche, being a system explicitly designed to obfuscate network activity to make it difficult to impossible to track back to the originator.
Most people have absolutely no need to use Tor, but it's clearly very useful for child abusers looking to not get caught. That study reported 80% of hidden service visits were to paedophile websites. This really is not comparable in scale to how electricity, the internet, storage devices, and so on, are used.
The linked study revealed that around 80% of hidden service visits were to paedophile websites.
Is 80% of internet traffic child pornography imagery? Are 80% of cars driven by paedophiles? If not, your comparison makes no sense really.
Also, Tor isn't public infrastructure. It's a largely anonymous group of people who have collaborated to form an anonymising network. Everyone involved who is aware of the above is knowingly enabling the sexual abuse of children, by allowing the perpetrators to hide behind their network.