This is really a Sh*tty topic LOL
The solution is an easy 2 step answer
#1 pick up your dogs crap
#2 take 2 seconds and bend over and pick up some other dogs crap...Its wont kill you and you might be sparing your own dogs health but keeping dirty poop away.
So, should owners pick up their own dogs poop... Absolutely! However, if they don't it wont hurt them, but it may hurt you or your dog.
I personally pick up crap even tho my dog only poops at home (shes shy), but I also say something to the non poop picking up owners of other dogs.. Shame goes a long way...
Maybe we should take pictures of the violators and post them in a thread entitled "public poopers"