I have heard about about those, and they probably could carry as much as a small car, but do they work anywhere remotely hilly? Hauling your own weight up a hill on a normal bike already sucks, unless you're really really good at it. You could add an electric motor to do most of the work, but at some point you just have the car again. Looking at the physics, human power provides maybe 50 sustained watts, and there's only so much you can do with that.

It's a matter of degree. You have to plug in your EV, and on the rare road trips have to plan charge stops. That's it. Getting on a bike is completely different experience, and for the majority of people at least in North America, would require a relocation and complete change of architecture to really fully be possible. And a significant minority would still need motor vehicles for their job.

Can't vs. won't might be an important thing to bring up here. Even if it can and should happen...