If you can understand changing gears on a modern ice auto using the paddles, then it’s not beyond the average driver to quickly get to grips with using it for regen.

Teslas have a CVT. No paddles.

And I’d like to know why one-pedal regenerative braking would be any more economical than two-pedal.

Incidentally, hybrid cars have had two-pedal regen braking since 2000 (and before that in Japan-- the Prius came out there in '97).