Surviving in the Wild

My question is this or perhaps it should be questions. There are natural
ponds all over the place, many with fish in them. No one cleans them,
watches the PH, the ammonia, or anything else. Some have inlets and outlets
but most do not so the only fresh water they get is from rain.

So how do these fish survive? I had goldfish in a pond for over nine
years. Since I lived about 200 miles away, I did nothing except feed them
when I did happen to be around. Those fish grew to nearly a foot long.

When we had our house built on the property, those fish vanished after all
that time. The builders said it must have been raccoons. I am quite sure
the raccoons looked like humans to the fish.

So, why do ponders have to go to all that work for fish ponds.