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.