fwiw, the roads are constantly littered with accidents and the US has the highest pedestrian fatality rate out of all "western" nations

It's both because there is more than one kind of road.

America really likes stroads which give the impression that you can safely travel at speeds that are actually dangerous. We do that often in neighborhoods where we should be going 20-25 max but the design of the roads encourages us to drive faster. Since the speed limit is often actually at a safe speed, the issue of speeding is about the design of the road and not the speed limit.

Larger roads like highways, freeways, and expressways are designed for high-speed travel but often have speed limits that are low for the sake of revenue generation. If you've ever driven through a small town where the highway design doesn't change but the speed suddenly drops from 65 to 35 you know what I mean. In those cases the problem is with the arbitrarily low speed limit as some states have raised the cap up to 80 and have not seen a substantial increase in accident-related injuries and deaths.

Connector roads often suffer from one or the other problem listed above. They are either designed to make you feel like you can go 60 when you should be going 40 or are set at 30 when you could safely go 40. The road design needs to match the safe speed by making drivers feel unsafe when they exceed that speed and not unnecessarily penalize them by not putting the limit lower than that speed.

Both of those result in speeding but have different causes.

It's both. They make it so you want to speed so they can generate revenue. Wide lanes and low speed limits can yield a lot of tickets

Well, both.

If the road were clear around me, I could easily hold 100+ off the highway. I've got huge streets near me with long curves. No problem for my relatively new tires and well-maintained vehicle.

Once we add cars to the mix, I can no longer go that fast. Too many other cars, if I just weave around them, I can go fast again. Who wants all this power sitting behind a Sentra?

Yay! I'm free! Fast fast fast until more cars again. A little bob and weave... Crash.

This road is literally as wide as the highway but the speed limit is 45mph.

The road always has traffic, always construction, always debris from poorly maintained cars or accidents which means you can't go fast but the road itself was designed for the Daytona 500. The 'speed limit' is set for a pace that makes 18 wheelers look fast.

So, the obvious answer said by every Suburban with scrapes on the side and Altima with paper tags is "My car isn't going to fail or crash and in ideal conditions should have no problem redlining all the way down this thing so I should try that in five o'clock traffic."

Um they are