TL;DR: The tester did not appreciate that lifting off the accelerator pedal causes regen braking, and thought it was having braking problems, since it was braking on its own without the break pedal being pressed.

Also, since the applicant was not always using the brake pedal, (because he using the regen brakes to slowdown first) she failed him for improper braking.

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Driver Testers, just like firefighters, need to be taught how EVs differ from ICE vehicles.

This TL;DR doesn't seem to reflect the article. My take from the article was that the DMV tester did understand how regen braking works but thought the use of regen braking prevented demonstrating one of the skills required to pass the test. The tester even advised to bring a non-EV vehicle when re-taking the test which indicates they knew that regen was a feature of EV vehicles and that the particular vehicle was not having brake problems.