I have 2 big dogs and yes I have trained them to poop on command. Although they will poop when they think they need to poop, one will do it anywhere she wants to (but generally waits until we get to the park) and the other will only do it on grass coz he's a softy (GSD).
It is always picked up and disposed of in the bin, never hung in a bush and none of us can understand why some do this, if you got it in a bag then take it to a bin - round here there are bins all over the place (council owned wheelie bins that people leave out front lol).
The problem is not the dogs or their poop, its people. People will be people no matter what the subject is there will always be those people that do stuff that is just not right.
They give us responsible dog owners a bad name and ruin what little areas we have for walking them by their behavior.
There is a sign in our local park quoting about 6 anti dog bylaws, yet there is not 1 single anti chuck rubbish and glass on the floor bylaw quoted, as such their is little dog poop about but always human rubbish to see.
Neither of my dogs are "not nice" in fact they are both very nice, they don't try to maul me like the cat does.
Dogs are wonderful and I wouldn't be without one now. Kids and other people I can do without.