So you're saying that the normal P is just applying just enough pressure on the brakes to stop the car from moving and if it was on a hill it could possibly roll away? Why would the normal park not be "maximum pressure"? Why does the engaging the "handbrake" cause a secondary action that makes a mechanical sound?
Applying maximum pressure when it isn’t necessary can wear out the motorized calipers more quickly. This was explained in a previous version of the owner’s manual but is not present in the current version.
The extra mechanical sound is from the motorized parking brake calipers applying additional pressure.