I have a different take. Every time I stop the FIRST thing I hit is the parking brake pedal. Why? If I have a brain fart and somehow forget to shift to park, or an excited 75# dog decides to hit the shift lever and knocks it out of park... or any other numerous anomalies, it ain't moving. And the LAST thing I need 300 miles from home is our motorhome on a YouTube video leisurely rolling across a gas station parking lot.
Now... if the shift lever had some sort of fail safe (yeah I know... the brake pedal). But weird things happen... and one of them is being able to remove the key in any position from my Jeep Wrangler.
One is none (tranny pawl). Two is one (tranny pawl AND parking brake).