alt Hacker NewsThis was addressed explicitly in the video. It's far less efficient end-to-end, even though the gearing is theoretically simpler. Trains do it because diesel engines just can't produce the torque you need to move a train (at least, in the form factor of a locomotive), so they need to use electric motors.
He makes that argument but IMO it's not particularly well founded. He talks about his old Chevy Volt and guesses about the new Nissan series hybrids while ignoring Honda's current lineup of series hybrids. The Civic hybrid* meets or beats the EPA ratings on both the Corolla and Camry hybrids when on the same size wheels (18").
I agree in principal that there's efficiency to be gained by minimizing conversion losses, but Honda may be clawing that back with larger and more efficient motor-generators that only package well because no planetary gear set is required to connect everything.
* Honda hybrids do have either one or two clutches to mechanically connect the engine to the wheels at fixed ratios for highway cruising, but their city EPA numbers are still very competitive.