CO2 production is not an issue worth solving?

In seriousness, trying to "fix" American suburbs is another problem wrought with political issues of its own (See Trump's "Suburbs under Siege") message. Getting to the point where population density makes it feasible to have adequate public transportation in most suburbs doesn't like something that would ever be economic for large parts of the US. So you end up with situations where Mom, Dad, Son and Daughter all need their own cars for basic needs.