In Arizona and Nevada the availibility of service centers were way more than in 50 miles distance however In few of east coast states the situation was much better but nothing comparable to what i expereinced in Canada and yes mainly 401. I didn't do a really long road trip in Canada though, it was mainly in Quebec and Ontario.
That's just the thing. Western Quebec and South-East Ontario are highly populated regions of Canada that only comprise a small percentage of the entire country's size. There are vast areas in Canada that don't even have paved roads! You're pretty much shit out of luck in most of Canada. That's bad news for someone like me who is into extended road trips. It will get better though, not in our life time. Canada's population is still below 35 million.
The US interstate network, cellular network and the availability of basic mobility needs (fuel, food, shelter, sanitation) is absolutely marvelous when the sheer size of the country is considered. I'm amazed by it quite often. The country is barely 200 years old (in its entirety).
Americans like to whine about their crumbling infrastructure (and they're right to an extent), but the fact that such an infrastructure even exists in this magnitude is quite a feat itself.