I can see why people are saying "it's just a bin, as long as it's bagged..." etc.
But it's the attitude of the dog owners - I'd be too damned embarrassed to do that in case someone was watching me. Because you are basically just dumping your waste on someone else.
Take the bag of poo home - your dog, your waste, your problem.
As for those who hang the bags on trees and in the hedgerows - a huge, whopping great fine is the answer.
I live in a terraced house along a main thoroughfare... people have put bottles, cans, food wrappers, food - and all manner of rubbish in my bin, sometimes filling it so the lid won't close - and then they dump it in my stone flower-planter instead. Inconsiderate, selfish and completely lacking in manners and courtesy. Oafish behaviour.