As for rear drum breaks, they are only an assist. If they go out, it just makes the front breaks wear faster.
They're also quite useful when you're not driving the car.
Doctor: Oh you're feeling suicidal... and so on and so on.
I'm sorry, but I don't get it. Did they manage to kill the fly in the end?
To further improve the safety of red-light cameras, consider that almost all rear-end collisions are caused by people tailgating. If each red-light camera were turned into a combination red-light and speed camera, people would slow down when approaching intersections, so someone slamming on their brakes at the last minute would be less likely to be hit from behind.
I don't think you were saying that rear-end collisions are the fault of the car in front, even when they brake suddenly, but I think it's important to say that any rear-end collision is the fault of the car behind. It doesn't matter how sharply the car in front brakes, you should never be so close that you can't also stop safely. Suppose that instead of a red light there's a child running into the road; the car ahead may brake very sharply indeed, but if you're behind and you give them another push you might just make the difference between near-miss and tragedy. Tailgating needs to be treat more severely than speeding if you ask me, or at least enforced... at all.
What about the driver? Drones don't have those. Trucks may be cheap, but they're useless without a person to pick up each package and walk it to the door.
I picture a hybrid of both: a truck can deliver heavy items and act as a pickup and recharge point for a number of drones dealing with the small ones. This way the number of drops for the driver is reduced and the drones' problem of range is side-stepped.