The radar does most of the work, the cam is supplementary. Too bad not all models have smart cruise control then it is easy to tell. You can put a piece of aluminum foil over the radar and drive around the block. you should get a blockage warning.
I had an instance where I was driving at about 35 MPH, the car in front of me made a sudden stop and before I could hit the brake, the FCA kicked in just as I raised my foot for the brake pedal. It sounded and felt like the anti-skid braking you would get on ice.
The warning beeps will go off on my Kona when I approach a T intersection where there is a tall building. "Look out! There's a building stopped in front of you!!!" Husband's Ioniq goes off EVERY TIME he comes up the steep hill to our house. It reads the road, especially where there is a sharp turn, as an obstacle. I turned off my lane keep warning (except when turn signals are used) because it reads tire marks and road grooves as lane indicators!