My own view is that cycling safety on roads depends less on infrastructure and more on the type of people with whom you share the road. Areas that have a higher "moron quotient" are likely to be less safe on all kinds of roads in my view.

The thing to note is that there's often a trade off in terms of what people perceive safe in regard to infrastruture. The less trafficked roads are likely to be narrower, so there's little room to avoid the few cars you're likely to meet. Conversely, you might experience 1,000 cars more/hour on the highways, but they're much easier to deal with if you've got a shoulder and there are several lanes.