We've created a national infrastructure that IMO nearly requires driving to be a civil right. That sucks. But I really don't have an answer to this problem when proposals to address this are either voted down or end up ridiculously over budget.
Considering the sheer vastness of the continental US, it's not surprising to me that there haven't been many good plans to remove our dependence on cars. The only options, really, for good nation-wide transport are trains and planes. Trains have an incredibly expensive infrastructure, especially the high-speed trains needed to traverse the thousands of miles between the East and West coasts. Planes are slightly less expensive, but the pain of needing to show up three hours early for a one hour flight, risk of lost luggage, and general fear now associated with traveling by air make planes a less than attractive option.
The US "sheer vastness" is irrelevant. Most of the US population live in states with a population density higher than countries like Norway, which have good public transport (only 10 states, with an aggregate 12 million people, have a lower population density).
Nobody cares if "empty" areas in places like Alaska have poor public transport. You get 90% of the benefit if there's decent public transport in the higher density regions.
Most transport is not nation-wide, but short distance commutes anyway. Even places with very low population density tends to have some places where public transport is useful. It's not about eradicating car use, but to reduce the number of journeys for which they are required.
EDIT: And the US as a whole has a population density twice that of Norway.
EDIT: And before anyone brings up the oil: Most of Norways transit infrastructure predates the oil with a significant margin.
Long-distance and regional transport needs are significantly different from local ones, and different land-use and activity patterns can hugely reduce transportation needs. The fact of a large country doesn't mean that individual urban areas can't be designed for mass transit or walkability.
If you can find shopping, school, recreational, and work activities within a few blocks (or at most a few miles) of one another, then a car becomes more a nuisance than a requirement. The exceptions become trips out of town -- the outdoors, visiting friends, etc.
Shopping can be dealt with through deliveries (scheduled and bundled, or online). Or local pick-up and a cart, wagon, or bike trailer.
Trades and crafts will still likely require transport, but that becomes an outlier exception.
Depending on what long-term fuel and economic trends look like, I suspect the US will see either regional high-speed rail or plain-old conventional slow rail. Aviation with expensive fuel becomes an expensive proposition. Roughly half a large jet's take-off weight is fuel, and for an efficient airliner at 40 passenger miles/gallon, a 3,000 mile flight involves 75 gallons of fuel -- at 6.8 pounds per gallon, that's 510 lb. of fuel, 2-4x the weight of a passenger. And while trains can be electrified, the options for doing so to aircraft pose a few larger technical hurdles.
But people don't commute across the US, just like they don't commute from Brussels to Madrid. Cities in the US are crap for a variety of reasons (racist zoning, defunding of transit, forced car infrastructure in the form of parking minimums, absurd NIMBYism, etc.)
