Dogs are not wolves, and have significant genetic differences that result in behavioral changes leading to domesticity. However, what Doggtyred said is utterly true. Dogs that attack people are improperly raised and conditioned. There is usually no reason whatsoever for them to attack other than the mistaken and ignorant actions of their owners.
Good example. The %^%$&&@!! toy poodle that bit me was then scooped up and petted by its owner. She reinforced this horrid behavior. If my dog did that he'd have his head pinned to the ground for his efforts, and he would remain that way until he submitted.
People hate yappy little dogs. I own one. He barks, it's his nature. He barks outside, it's time to come in, and he knows it. I don't like yappy little dogs either, and I won't let mine be one. Simple measures of control can make a dog's behavior far more acceptable.
The city/county comparison is just plain stupid. People in the city by and large don't use dogs as commercial entities, rather as pets and companions. Honestly, what sort of work is a dog supposed to do in an urban or suburban setting? Lots of people on farms also have dogs that are pets, and I've seen them drop some serious coin to keep them healthy.
And their are plenty of stupid people on farms who do lots of dumb stuff to dogs, just like there are in the city. Fewer in the country, because there are far fewer people in the country than the city.