By this logic nobody should be allowed to own a pool. Instead we require pools to be fenced, which is the same thing people do with guard dogs.

Pools don't jump over fences, though.

In what reality are kids inadvertently wandering into junkyards and getting harmed by junkyard dogs in large numbers?

Kids were brought up as the reason that pools are fenced. Because adults tend to have motor controls and an understanding of their ability to swim, so pools aren't usually a danger to adults.

By contrast, people of all ages can be bitten by vicious dogs ... and shouldn't be. Yet, they are, in large numbers.

Dogs go to the vet. Dogs jump over fences, they run out open gates. People go to junkyards. There are many opportunities for a junkyard dog to interact with people it shouldn't bite.

But kids do.

No, the small children who are at risk for falling into a pool do not jump fences.

Regardless, if your pool had a history of safety issues, you should be expecting attention from regulators and insurers. Query your favorite search engine for "pool closed following death"