It would be about $5 Trillion dollars to connect all the small communities and rural areas of the USA and that would not actually get people from their homes to the store but it would be close enough people could carry a folding bicycle assuming their shopping demands are light. That estimate is just for initial construction, not ongoing maintenance costs vs the existing roughly $500bn to maintain the existing highway system.

Cost aside this is of course problematic as many of the vehicles in my rural area are hauling horses, cattle, other livestock and vegetable produce. They won't let people take a herd of cattle on the tram and there are only a handful of open access paths that people can move cattle the original way. This gets even more complicated with things that can not walk on their own like assorted crops. People are not permitted to take 25,000 pounds of grains, fruits and vegetables on the tram. A full sized train could do it but there would not be a full sized train going into every small community (though it would be quite a sight to see). In every practical sense full sized trucks and large tractor-trailer trucks are required to move produce to the full sized trains and then tractor-trailer trucks from the train to distribution centers or your grocery stores will no longer have produce.

Even without the cars the roads would still have to be maintained and very few people would voluntarily give up their cars. Most would put up a significant fight and/or everyone would just buy big trucks and stick a ranch decal on the door.