In my experience, the majority of crashes (aside from actual mistakes) are caused by people attempting to overtake at the absolute worst times possible (85% of which is on the C-D road), regardless of what speed the truck (or trucks...) ahead of them is going or if there's even a truck coming the other way.
100kmh isn't enough for some people, it's all about "getting the overtake" for them regardless of how little sense it might make.
Behind that, its people who do full speed around every corner and expect the truck or car to just not have any issues and as such aren't even prepared for what happens.
As for people doing the speed limits, it can't be considered reckless driving because its the actions of other players around them (such as doing 110kmh on a 60kmh road and overtaking at inappropriate times) that are reckless.
If they only do 60kmh when there's people behind them and speed up as the other players try to pass, then its considered blocking.
With the people who don't go at green lights...I suppose that's where the game gets a little too realistic
Keep in mind, everyone enjoys games in different ways and changing the way players drive would never fix the C-D road