Now, I am not nor have I ever been a dog owner. I like dogs, but they require more care and attention than I have to give right now. Someday when I live in my own place with a yard or a lawn, this may change. Who knows. Of course the other reason I have resisted dog ownership is the need for walking. And the corresponding need for scooping. Sure I have to dispose of my cat's stuff too, but I have a automatic litter box so I scoop up the stuff from one convenient receptacle into another. And try not to think too hard about it.
But I feel certain that there are rules about doggie stuff. Such as, you should not let your dog do stuff in other people's yards. Or on other people. (hey - it happened to me - sitting in a park and, I thought, minding my own business. Ruined a really cute pair of shoes.) Yeah you can't really make your dog relieve itself exactly when you want, but it would seem you certainly could control bits of it, by controlling where your dog walks. After all, you manage to keep your dog out from under moving cars, I assume, so you have some control. Other people's yards are the same. Especially their gardens.
Over at the Rage Diaries a fascinating discussion is developing. Lisa and her spouse noted people letting their dogs pee in the potted plants they have placed in their yard. Plants they had been hoping to consume. In each case the owners moved their dogs after being directly asked about it. Although not until the dog had already emptied itself. And I realize that cats that roam free probably do this too. It's not that I feel cats are exempt. If I was standing right next to my cat, I would certainly stop her. Right now my cat doesn't go out anyway, so yes, it's all very easy for me. And certainly, the joy of growing things outside is that they are exposed to, um, all sorts of stuff. But, stuff that just happens is very different from stuff you essentially lead your pet too.