> I would like to see laws allowing extreme low-cost vehicles (equivalent to golf carts, I guess) allowed on designated roads. A special inexpensive insurance proviso for them.

These already exist! You maybe haven't heard about them because they're largely a failure beyond niche applications. They're mostly used for things like hospitality shuttles, facility maintenance, meter maids, etc.

https://en.wikipedia.org/wiki/Low-speed_vehicle

https://en.wikipedia.org/wiki/Neighborhood_electric_vehicle

The problem is that they don't make sense for most people, e.g:

1. You can't operate them on high speed roads. The US has a lot of high speed roads, particularly in areas that are poorer.

2. They aren't cheaper than a used car. A street legal Cushman or GEM starts at about $16k. A brand new Nissan Versa is only about $1-2k more, is wildly better equipped, and has more accessible financing. Good $10k used cars are available on every street corner in every poor neighborhood with extremely accessible financing.

3. They are weird. It is much more socially acceptable to drive a similarly priced used car.

4. They lack features that used cars have. Many control cost by omitting basic features such as doors and climate control.

5. The places where you can use them (low speed neighborhood roads) are already more likely to be accessible by alternative means of transportation. (busses, bikes, walking)