Gee, I'd never realised that cats aren't dogs, thanks for pointing that out. I assume that you believe dogs should go round in packs, seeing as you're so keen on "natural" behaviour?
Anyway, you don't take responsibility for your pet - you allow it to crap in your neighbours' gardens. Have you ever been round to your non cat-owning neighbours to offer to clean it up?
Clearly you've such a limited understanding of the English language that I'll have to make this really really simple for you. Under the law, dogs must be controlled, lest they cause a danger or harm to people/property, which is why when a stray dog craps in your garden you can, under law do something about it, even if it's just prosecute the owner for trespass.
I do take my responsibility very seriously, I feed my cat a diet that is suitable to its kind, treat it in a way suitable to its kind, and allow it to have a suitable surrounding and area for to roam, with such stimulation and environment to allow it to behave in away natural to it's semi domesticated nature.
Cats do not present the same risk of danger or harm, so cats are not, under the rule of law, able to commit the offences that dogs can and do. So cats are free to roam where as dogs are not. If dogs were free to roam there would be a whole lot more shoot in your garden than there is now.
Until a year ago I was a non-cat owner, and unlike several people here, I have accepted that cats will crap in my garden, as will badgers and foxes, and other urban/semi wild animals, and I, being the one gives a shoot about the state of my garden and having a young child, I would have to clean up their mess. Now no one is bitching about foxes crap, or badger crapping and not even covering it up. Cats are animals that are allowed legally to roam, so like birds and other animals there is nothing that needs to be, or can be done.
Apply Rule#5.