validation rather than empty praise, and it really worked. And saying "Thanks, I appreciate that" is different to saying "good boy/girl" - it allows that you have feelings that were considered and allows the other person to either acknowledge that their action made someone else's day better and that's a reward in itself, or feel upset they didn't get a gold star (or whatever). It brings about a more caring and empathic society - or that's the theory anyway, if everyone bought into it.
I have trouble seeing the difference between the validation of "Thanks, I appreciate that" and "from one mum to another thank you for breastfeeding in public and making it easier for other mums to do the same". I'm not trying to be smart or cause argument, I honestly don't see much difference. What was written on the card was (to me) is a more thorough "Thanks, I appreciate that". It's very possible that the person that gave out the card was also a breastfeeding Mum that finds it difficult to breastfeed in public, and that seeing other Mum's do it makes her feel more confident to do it as well.


I was also thinking about the whole "preaching to the choir" thing. One thing that I think the cards do is get people talking about breastfeeding in public. A Mum breastfeeds in public, gets given one of those cards, talks about it with her friends, maybe even posts about it on facebook/forum/other social media, which gets people talking about public breastfeeding. This chatter might make other Mums that are more self conscious about feeding in public feel less alone, and that in itself might make them more comfortable doing it herself.