There's nothing rational about refusing to believe data you don't like [...] It's good to have an absurdity filter [...] But you need some kind of reason

Perhaps it might be more productive to ask oath why they find the numbers unbelievable?

two things that are, in fact, identical

In a culture where spanking is regarded as normal and (say) starving your child or making them have sex with you is regarded as appalling, there is a very important difference between spanking and those more dramatic kinds of child abuse: that it's widely regarded as acceptable. That doesn't stop it harming the children it's done to, but it makes a big difference to (for instance) what the fact that someone does it tells you about them.