That's because that's what it used to be called. In the owner's manual. I imagine the change might be due to liability more than anything else. That, and just marketing. No one wants to imply that you'll have an emergency in your shiny, new Chrysler.

These things are wimpy brakes that are designed to prevent a vehicle from rolling if parked incorrectly or on a hill. They are generally cable actuated and don't have much stopping force if the vehicle is in motion.

Fifty years ago, this would describe most brakes on consumer vehicles [0]. They're wimpy because they're drum brakes (though more upscale vehicles have rear discs). They are difficult to modulate because they're actuated by flexy cables. But cable-actuated drum brakes were what you got when you bought a 1960 Chevy.

As for stopping force, a parking brake should have all of the stopping power that the rear brakes usually have. The reason they often don't have much stopping power is because most people don't have them adjusted regularly (meaning the cable runs out before the full power available is applied), or more commonly they don't use it at all and the cable rusts up. If properly maintained, you should be able to lock the rear wheels at speed.

[0] EDIT: give or take. I don't remember exactly when cars went hydraulic, and the web's no help. I did own a 60's Harley/Aramachi motorcycle that had cable-actuated brakes, FWIW.

Some car manuals actually labeled it "emergency brake".

Secondly, is it considered a mechanical failure when the master cylinder fails and the driver is too slow to find the emergency brake actuator in time? Self driving cars do not suffer from that problem.