It is a Safety measure, set up your navigation before you start driving so you can pay attention to your driving. With Android Auto I set it up with voice commands while moving.
The sound and volume are mandated by the federal government. If everyone could have their own sound the blind people wouldn't know what it is. That is the problem when you don't keep score in little league , you get a generation of people who believe the world rotates around them.
Lane Assist uses the rear brakes to pull the to vehicle back to the center of the lane, by applying braking to one wheel. Cruise control is trying to maintain speed against the braking, so it uses more fuel.