If it’s a revenue generating machine, the impact of 10 or 20% improvement in day to day could recoup the additional cost in a few months or a year.
Similarly, for someone who travels a lot, having a useful battery life of 8-10 hours of internet+video playback allows a work routine that is worry free wrt charging and this allows tighter travel schedules.
Ofc, this isn’t the case every time, but this creates anchor effect on several segments of the market. This also doesn’t include the extra cost of “luxury” aka thin and light or small bezels.
350 USD is perfectly fine if you don’t need a ton of battery life or color accurate screen or multimedia or multicore workloads. If you need any of this, most of the options get pricier than 700 USD. It’s not uncommon to have to shell out 1500 USD or more for the desired specs.
The OP is correct wrt powerful e bikes sharing space with pedestrians and normal bikes.
They are a different beast, heavier and noisier. They have much higher speed limit, and require less effort (some models need no pedal power) to travel. This, alongside the rise of delivery services, encourages people to overspeed (more than 20mph).
15mph is roughly the limit of what makes bicycles safe for mixing with pedestrians, but beyond this speed, they aren’t that different from a motorbike in terms of road design considerations.
At least they are better than cars and SUVs