On a per mile basis, they most definitely are not. Here's one set of US DOT numbers[0] from 2007 that show the rate on interstates is 0.7/100M miles while the rate is highest on collector roads at 1.99/100M miles followed closely by local roads at 1.94/100M miles. Interstates have less than half the fatalities on a per mile basis as local roads.
Absolutely not the case. If you're driving from A to B, you have to cover similar distance regardless of type of road. (Yeah not conpletely true.) It turns out that highways are both quicker and safer, but the two are not necessarily correlated.
If you expose yourself on a live fire range for 1 second and travel 100m/s, it's far less dangerous than exposing yourself on a live fire range for 100 seconds travelling at 1m/s.
It's the same thing with cars, the longer you are physically on the road timewise, the longer you are exposing yourself to the chance of an accident, regardless of distance travelled.
Not sure why you think it's "absolute", you haven't listed a single reason or argument, just a tautology.
The analogy is poor: on a live fire range the bullets move much more quickly than you. The speed of the bullets relative to you is largely determined by the bullets, and your speed is irrelevant - so how fast you move is naturally irrelevant (assuming random fire, of course). The chance of collision will be determined largely by the number of bullet-meters made. If you will: it's as if the bullets are exploring the space in a probabilistic/ballistic fashion - the more bullets and the faster they go, the more they can explore.
Conversely, when you hit something on the highway, it's likely to be moving much more slowly than you (e.g. the chicken crossing the road), or at a speed similar to you (the drunk guy driving on the left side). So your speed matters - you're more likely to reach that obstacle in any given period of time if you can explore more space in that time.
That's not how roads work, the average speed of a road isn't simply the max speed of the road. Especially not in towns, compared to motorways, which will skew it heavily towards motorways.
Again, not true, you fundamentally misunderstand the majority of car trips.
If my job is 2 hours away because there is no motorway, I will get a different job. If there is a motorway, making the commute 40mins, I will take that job.
People care how long the journey is, not how far the journey is.
People live by commute time, not commute distance. Same for service areas, if the roads all have low speed limits you would need more drivers, they wouldn't just drive for longer.
Personally when facing decision between highways, local roads and other means of transportation I almost always have a specific destination in mind. Accidents per mile is the statistic I want.
Accidents per hour of driving would be more useful for public policymakers – given fixed average commute 1 hour per day, what's the tradeoffs of building highways (worker mobility, commerce, pollution, landscape, accidents).
Out of curiosity, if the motorway is shut down due to an accident or construction, would you drive for 40 minutes and then pull over to the side of the road and work from there?
[0] http://safety.fhwa.dot.gov/speedmgt/data_facts/docs/fataltbl...