Increasingly, modern car drivers are enclosed in noise dampened, environmentally controlled environments with some sort of sound entertainment playing (music, podcast, talkback radio). So car drivers are less able to make good use of sound and other cues for detecting other traffic.
The lack of sound from hybrid cars, for example the Toyota Prius when accelerating in electric mode, has caught me by surprise while cycling. Not knowing you are about to be overtaken can be dangerous because there is an instinctive fight/flight response which can cause a sudden flinch or overreaction away from the surprise and you naturally turn your head to look at the perceived danger. As you are normally cycling on the edge of the roadway there is a higher potential to now accidentally ride over/into an obstruction (drainage grate, kerb, pothole) and come off your bike.