You see the occasional dog poo but you do not see the fast food litter that's strewn everywhere?
The litter that will take many many years to break down as compared to the poo that will be gone after the next rain.
The local tidy up campaigners have done little pickup the poo pictures sprayed on the paths, I counted 17 within about 30 yards last time, they look a bloody mess.
Now the nicer weather is arriving we are going to get more and more bottles, beer cans, single use bbq's etc. in the local park - far far more than the occasional poo.
I too am annoyed when I see un picked up dog poo, IM waiting til I actually catch someone in the act - they will be offered a coupe of bags as they have obviously forgot theirs.
I always have dog bags on me even when im not out with my dogs.
The problem is people, they are lazy barstwerards, having a dog is nothing to do with it - these are the same people who leave the fast food crap all over the place spoiling the area.