Recently had a loaner Mazda CX-5 crossover/SUV from a dealer while my other car got worked on, and noticed the early-warning notices in the systems are getting better and better. Had it warn far in advance of a stopped vehicle (when it thought I was approaching too quickly). Had it even warn of a cyclist, on one occasion, though I don't know how effective that aspect really is as compared to the car-approaching warning. And this isn't even a car with so-called "auto-pilot" type stuff. Altered the settings, to evaluate how responsive the system seems to be. Not bad, for a current system. Hardly sufficient, however.
It's all improving. As you say, something integral to the RADAR/LiDAR systems is going to be necessary to catch more of these situations. With a big-rig truck, though, they're so heavily-laden I wonder how much can be done in a scenario involving a much slower vehicle about to be struck.
Though, as the A.I. involved with decision-making in these technologies continues to improve, I'm hopeful that in a handful of years we'll have much more capable systems trickling down into a lot of cars.
As a cyclist, as well, I know that'll be a really nice day, knowing it's vastly less likely I'm about to get struck from behind. Someday.