Mogz that sounds so lovely 
I would really like to see the RSPCA step up in this respect, I have my own reasons for having a poor opinion of them but as such a recognisable brand and with significantly bulging coffers (centrally) they are in a great position to reach non dog owners. If you are not 'doggy' but have concerns or a problem with an animal many people will immediately think of them. They have the power of prosecution, they are on tv, the internet, it would be nice if they actually made their campaigns more visible.
Dogs die in hot cars is fairly well entrenched - although I have seen more from the Dog's Trust on this than the RSPCA - but others just don't seem to be promoted as well as they could be.
After all this is not 'just' a dog problem, if parents are concerned about dogs and child safety actually using the resources available would be sensible. If they know what, and where, they are.
I don't actually have a better answer to the problem than that though, maybe linking up with schools or children's charities? Unlikely.