Fishing doesn't work as some would expect

Trying to catch fish is not working.

Tested with a fishing rod with Lure VIII in an ocean with nearby fish.

Tested again with fishing rod with Lure III. It works but not what I expected. I expected fish mobs to go near it and get hooked but the same fishing mechanics was the one I experienced. What's the point of having fish that you can't catch with a rod?