Busy roads and cats aren't a good mix, we chose our place on the basis there are no busy, fast roads nearby and have actively discouraged them from going out the front where the road is. Some cats are more savvy about traffic than others but cars are the number one killer of felines (and just about every other form of wildlife, including cyclists).
Cats that have never been outside generally don't seem to mind, though you need to keep them occupied for the twelve minutes a day that they are awake. Once they've been outside, keeping them in is a challenge. Sometimes they can be persuaded to stay away from the roads, ours rarely venture outside of the back garden and that of our neighbour. You have to watch them, once cats have a path, they generally stick to it. Boy cats, of course, will wander further.
The cats decimating local wildlife (in Britain) makes little sense to be honest, it just limits the population and opens up opportunities. Birds don't have substantial natural predation. The same is true of cars to be honest, though it's horrible to see dead foxes and badgers, it's doing much the same (and foxes and badgers have no predators other than people).