> I would love to see small cars like these come into more widespread use in the the U.S
While I agree with the sentiment, I don't think this is possible.
The first layer of the many problems is that people don't have unlimited funds to purchase multiple vehicles. Remember that every vehicle must also be insured.
This means they must make a selection based on life's realities. For a family, in most urban areas in the US, that means highway travel to go just-about everywhere, including shopping for food, school and work. A relatively small percentage of people in most towns have the luxury of living so close to work, school, stores, church, whatever, to be able to use this type of vehicle.
And then you have the issues you alude to: Speed and size. My street, which is in a nice neighborhood, is supposed to have a 25 mph speed limit. I can't tell you how many people who live here fly down this street doing 40 to 50 mph. It's mind blowing, really. If you can't be considerate in your own neighborhood, I hate to think what someone might be like on the highway.
I have almost been hit a few times in the 25 years I've lived here just coming out of my driveway. People are moving so fast that you look right and left, it's clear and, when you are on the road someone suddenly is right on your ass. It's terrible.
We've had multiple neighbors call the police for some enforcement. They put on a bit of a show and nothing happens (those signs showing your speed). They don't want to write dozens of tickets on a neighborhood street. They have more important things to look after, I guess.
And so, most people look at a car like this and think "That would be nice, but...".
I suppose there might be a potential future where self driving cars might be software-limited to maximum speeds based on where they might be and actually cooperate to increase safety (the car coming down the street knows my car is pulling out onto the street and plans appropriately, etc.).
I think that's the only hope really. Which means it is at least 25 years away.