There's a whole bunch of legislation that specifies what happens when you touch the brake pedal and how much deceleration needs to happen at every part of the i

There's a whole bunch of legislation that specifies what happens when you touch the brake pedal and how much deceleration needs to happen at every part of the input range. Any system involved in that needs to meet much stricter requirements. This also applies to regenerative braking on the accelerator pedal if the deceleration is over certain values. From what I understand manufacturers will actually have multiple "regeneration" modes to work around all this, but I don't have first hand knowledge of this particular area.