Erm, this was something I was picturing my (not abused, in case it needs to be stated) younger son asking him upon seeing this, so I'm not sure what your point might be in connection to what I wrote.

If your first reaction is to call your kid a liar when he asks you a question you don't understand you have more pressing concerns than lenticular billboards.

I think you are overreacting a bit. I'd just tell my kid that the kid on the ad had an accident.

There are much worse things your kid probably sees daily just by turning on the TV.

The scenario here is that your kid sees the injured child and you see a healthy child. You don't see the injuries to think up the lie that the kid had an accident.

Now I have much more sympathy for your point view. However, I still claim that "There are much worse things your kid probably sees daily just by turning on the TV."

No, but that's not the only problematic scenario. A child who isn't being abused might still see the signs in one of their friends, and you'd want them to speak up about it. Talks like the one mentioned in the grandparent post discourage that.