If we exclude farm animals and any animals that humans use for sport or eating this is most likely true.
I don’t have any statistics, I can’t prove it, but most people who get a pet probably want it. This is not necessarily the case with children. It is possible many people who get pets become bored with them but even if that happens it is not that likely they would actually go out of their way to make their pet’s life unpleasant. And although there are also those people who mistreat their pets out of neglect I suspect there are probably more who do that with their children.
For one thing pets just don’t live as long nor are they as demanding. And owners don’t have as high expectations of pets as they do children. Your pet doesn’t have to learn to play the piano, go to school or participate in sports or any other thing. Your pet is unlikely to be daily educated or have chores or have any real sort of expectation except just live.
Some parents are great with their children. But even these are torn by a society that expects them to work 40, 60 even 80 hours a week to get ahead. For these parents even if they want to treat their children well it is difficult.
Of course that is not really abuse but it is still a problem.
The type of abuse I am mostly speaking of is physcial and psychological. Physical abuse can be hidden, jsut as wives are beaten and the world mostly does not know. Spousal abuse is very high, likewise children. The difference is both parents can abuse the children. If the parents are “disturbed”, and there are so many disturbed people nowadays, why wouldn’t they treat their children in a disturbed way?