Skull1 you raise a very valid point. If you care about your dogs you should know whether there are traps set on land where you run them. Here in the very deep south, trappers are extremely cognizant of stray and even trespassing dogs. Bucket sets are rare, with most lethal sets either under water or up a pole. Personally I'm of the opinion that it isn't the dog's fault that the owner is an idiot, but I don't rely on fur for my income and don't want to judge.
The landowners in my block who don't allow trapping are farmers who live off their land. These aren't PETA folks from the city, they are hard-working people who choose not to allow hunting on their land. In my opinion, if you want to use dogs and you don't have permission from EVERY landowner between the roads, your only option is a leash.