In areas a bit more advanced than the one that I live in this is mandatory and you'll actually get a ticket if you don't pick up your dog's poop when taking it for a walk or having it run around somewhere. We don't really operate that way and when I am in a park or some public area there is a really good chance you are going to have to watch out for stinky land mines when you are there. This is just part of living here and you get used to it.
At least in Thailand, there are a lot of good reasons to NOT pick up your dog's poop when walking them, the main one being that we have a pretty terrible waste management system and you may actually be doing the world more harm than good if you are one of the folks that tries to "do the right thing" and clean up after your dog.
When I am walking my dogs I always carry a plastic bag or two with me just in case, but I actually very rarely pick up their poop because I know that if I do, and I put that bag into a bin, that the bag of poop is going to sit in a landfill for 100 years or it will be burned by the waste management people who don't have much regard for the environment at all here. We don't actually know how our waste is managed but I was out at the dump a few years ago do help a friend dispose of a bunch of stuff the trash picker uppers wouldn't take and a lot of the grounds there were smoldering which indicates to me that yes, they do burn the garbage. It seems to me like this could be quite dangerous since you never know what sort of things people have put in the trash. It could be explosives like empty paint canisters.
The point is, that when I take my dogs out I don't freak out once they pop a squat and unless they do so in an area where people are likely to walk, I just leave it there. They way I look at it the turds are actually good for the plants, and since we experience rather extreme weather here in Krabi, between the intense sun and heat, the huge downpours of rain, and the insects, that poo poo is going to be there for a day at the most. If i pick it up it ends up in a landfill or on fire somewhere and this is much worse than someone that needs to scrape some doo doo off of their shoe.
Therefore, I very rarely actually pick up after my dogs. Normally I will only do so if they decide to relieve themselves on some footpath somewhere.
I'm sure it is quite different in western countries and perhaps even criminal to not pick it up depending on where you live but over here where I live, I actually find it socially irresponsible to use the bags rather than just leaving it there.
Thoughts?