I do stand by my statement that a truck has never slowed down behind me but mostly because I get off the road when they approach and another vehicle is oncoming. I don't trust truck drivers in this situation
Car drivers are better. Most will slow down
So you jump off the road when a truck comes up behind you unless you have a wide shoulder, but stay on the road if it's a car, and that makes truck drivers more dangerous?
I guess I've seen enough interstates with road construction (and no shoulders), bridges across major rivers (with no shoulders), in mountainous terrain (with little shoulder), or widened to the point that there's little shoulder left, that I can't buy your assertion at interstate riding is going to be safer. For SOME rural interstates that may be the case, but remember that the speeds are typically going to be higher on an interstate than a road or surface street. Look at the skid marks and tire tracks in the median or off the side of an interstate's traffic lane, and ask if you want to be there when somebody ran off the road doing way over the speed limit. Add in having to navigate entrance and exit ramps in more settled areas, and I'd prefer to skip the interstate even if I could ride on it.
For the most part, I've found the AC routes to be well planned. There's a few areas where you have to be on that road to get there, but they've done a good job of identifying low traffic roads, with generally good sight lines, and if there's not good sight lines the road twists enough that most traffic won't be flying low.