I think there are approximately 20 million feral cats in Australia which they estimate eat 5 creatures per night. Also Australia doesn't have as many predators to help keep the population down. I have zero issues with feral cats being shot and I love cats, I think they are pretty awesome animals. I would prefer people spay their cats though so the population doesn't increase.
I've found a box of kittens dumped on the side of the road when I was on my way to work and ended up keeping them for a few weeks until spaces became available at the shelter my friend worked at. People will happily take kittens and puppies and then dump them later as adults and replace them with another kitten. It seriously makes my blood boil. Old dogs and cats are really special, they have substance and have been loyal for so long. I don't know what is wrong with people