That's another problem that doesn't need to exist. I never saw a fire hydrant until I arrived in the states, because the smart thing to do is put it under a hatch somewhere in the road.
How is it better when you can accidentally park on top of it? Sounds worse. Harder to access, access can be cut off by single car. A hydrant has 4 directions of flow, so works fine. I think we have the engineering well sorted.