Some people just won't be told.

Noticed a post on [a social network] about a dogue de bourdeaux that is kept in filth behind locked gates. Dog looks in good condition actually from the photo but obviously not acceptable living conditions.

A man comments to say people should go and give this poor dog treats and attention (completely agree) and that he always gives it the cooked lamb bone from the Sunday roast!

No no NO!

Try and nicely and respectfully inform this man that cooked bones must never be given, doesn't matter how many others say the same or what evidence he's given he won't be told.
Even when people say their dogs have died or almost died from being given them.

Oh no, only chicken bones splinter.
The pet shop sells cooked bone and they are the experts so it must be safe.

Despair sometimes.

Yes. This.

People in my community-- well-meaning, animal-loving people-- routinely put cooked lamb bones out, ribs and spine and legs. I have had to put my hand down my dogs' throats more times than I can count getting these things out. People are not malicious. They simply do not know that cooked bones are harmful, or are unwilling to believe it if we tell them: all dogs love a good bone, right?

Most people are great if you tell them about the dangers dogs face from human detritus (bones, chocolate, xyltol) and you will gain allies if you engage with people.