It is also done automatically via the brake pedal - one of the reasons reviewers often describe inconsistent brake feel on electric carsI've never driven an EV and maybe I'm missing something completely obvious but why can't all that be done automatically via the brake pedal?
So basically no regen so the car can 'coast' but when braking the braking effort is translated to X amount of regen right up to the point where the physical brakes have to join in. From what I've read about the amount of regen available in one pedal driving it sounds like by just driving normally there would be enough retardation through regen alone to do the bulk of the effort.
The paddles or settings just set up how much retardation is achieved on throttle lift off - it's better to slow down through regen only, rather than using the brakes which can happen if you smash the brake pedal. Basically it encourages you to slow down more gradually rather than risk using the brakes and 'wasting' energy