I don't understand this comment. There are tons of non e cargo bikes. Are you saying they're unsafe to use? You could simply walk the bike if the terrain is too steep.

There’s a reason why heavy cargo bikes originated in flat places like Christiania, and the Netherlands. Walking a Larry vs. Harry Bullit up a steep hill is hard enough empty, but with 3 kids and groceries in the bucket I can see a lot of people preferring an assist.

It can be much harder to ride those cargo bikes by pedaling and throwing your center of balance around when weighed down compared to allowing the motor to accelerate you while keeping the bike properly balanced.