50km/h deserves a $400 fine. That's obscene speed on a pathway.
Compare that to this section by the Inglewood bird sanctuary:
https://www.strava.com/segments/4135178. This leg, I have no issue with people going fast. It's wide, it's open, you can see the whole thing and it's fairly empty. But if you see someone, slow down.
Oh, and the entirety of Carburn park is 10km/h. I tried riding part of that at 10km/h this morning.. it's almost impossible to ride that slow.