May I suggest looking forward to what can be achieved rather than look back at what has not been achieved in the past. Why not come along to the conf on Wednesday and find out what has happened in other cities and places saying 20's Plenty.
Look it ain't a magic bullet, but it is a positive intervention that reflects developing public consensus and opinion.
It's a new era where local and national engagement can be coupled with light touch enforcement to deliver better compliance and behavour change. Sure behavour change through engagement is a bigger call. Winning hearts and minds is always more difficult than communicating via "buttocks and spines" (eg speed bumps) but in the long run it gives far better, wider and more consistent results.