> [...]$600 premium for electrification. But most people like mid-drives (torque-sense pedal assist), so it's more like $800[...]

I don't know about the US, but in the EU that "like" is a must-have, your bicycle isn't street-legal as a bicycle unless it's a pedal assist (pedelec). The cheap option of pressing a button to get power makes the bicycle an electric motorcycle or scooter, needing a license, helmet etc.

So part of why they're expensive in the EU & other markets is regulatory, a drive train that can smoothly mix motor and pedal input without being clunky is more expensive to make than an electric scooter.