(most) Newer cars will not let you remove the key if not in park. Many also have an electric parking brake as well that engages when parked. My car automatically goes into park and applies the parking brake when I turn the engine off. Several other cars I test drove did the same.
I never had the need to use the "emergency brake" in years of driving, so full on or off with the electric brake is not a problem.
Surprised that the Prius still uses cable activated brakes.
Ha! I often get out to the bleep reminding me to press the off button....however I always do, and always press the park button then apply the handbrake (which is a pedal foot brake!)
The Prius doesn't have an ignition key, a power button turns it on and off if it detects the key fob in the car.
Many new cars don't require a key to be inserted now a days to start.
The Prius should go into park when powered off.
I think electric parking brakes are less common than keyless entry and start systems. Either way, sticking to the cable brake is an easy way to save money for the company.