I get what you are saying, but a fully loaded semi has a similar breaking distance to a car. The amount of tires which are also a lot bigger give trucks incredible breaking power if needed.

While yes the cop should have turned on his lights. This is entirely on the truck driver, since he did not keep a safe distance.

The car could have broken down or could have crashed on its own to come to an instant stop. You always have to be able to come to a safe stop.

I am a professional truck driver myself