It's a tough one. I think it's something you discuss if it comes up, you know. This is what we do.. I read this interesting thing... and that's why...
Oh, I read this great book... it's really helped me. Or something like that maybe? Some people will take it for what it is, but some will get defensive and take it as a personal attack. I guess you just have to judge your audience.

As for that mother in your MG. I wonder, perhaps she only waited so long because people were there. Maybe she wouldn't normally have left him so long, but she was worried about being judged as too soft, or whatever. I think we all worry overly about what others might think. It's a shame, isn't it?