Think of the way you change the volume on the car stereo when you don’t have attention to spare. It is a single instinctive motion. Your body knows approximately where the stereo is on the dash, so you reach for the volume knob instinctively. If you have to look at all the glance doesn’t last longer than it takes to aim your grasp in an approximate way. One you have the knob in hand you don’t use your eyes to see how far to turn it, or in what direction to turn it.
This is crucial for driving safely. Your attention belongs on the road.
Apps on a mobile device with a touchscreen don’t have this advantage. You have to read the screen to learn where the controls are.
So haptic feedback on a touchscreen phone is a milestone for mobile apps for drivers.