Being dependent on a car is not freedom.
The reason America has given up on mass transit or public transit for the time being, is because America is in the middle of a culture war. One side coerced the other into advocacy for petrol-fueled, privately-owned and personally-financed motor vehicles. This enabled driver licensing, vehicle registration taxes, collection of interest on bank and credit union financing, and empowered the overwhelming majority of the police state. It was just bad for the environment because of particulate and carbon emissions, and bad for society because it drove suburbanization, urban sprawl, increased congestion, traffic, and ever growing highways. Mass transit was always an alternative to those things, but its widespread adoption would upend or disrupt long-standing traditions that underpin so many mandates. Your driver's license is your fundamental ID in US society, and it's questionable whether the government has the authority to mandate any other ID. Registration, fuel and impending per-mile taxes fund transportation infrastructure. Auto loans account for nearly $1.5 Trillion debt every year. Traffic enforcement and patrol accounts for the majority of police work by far. Responding to violent crime is typically around 1%, but patrolling roads and streets accounts for nearly all police interaction with the public, citations, revenue generation, and arrests.
The left could have adopted a position advocating for mass transit to realize sound environmental and sociological goals, but its adoption would have threatened the expansion of the state's power. Public transit might seem to expand state power at first glance, until all the factors surrounding individual motor vehicle transit are fully considered. Anything that diminishes that without completely eliminating it, reduces the impetus for state control.
Instead, the left is betting on a state enforced transition to a disruptive technology that won't solve any problems but that will maintain everything I've mentioned. The state built the current transportation infrastructure with leftist support, and rather than conceding its flaws, the left is hoping "technology" will fix the problems. Compared to advocating for mass transit, it's a winning position because even their opponents on the right have been conditioned to believe that being dependent on a personal motor vehicle is "freedom." Even when they're driving trucks made in China, fueled with Arab oil, and controlled by Apple, being tracked by GPS transponders, paying a per-mile tax, interest on the bank loan they financed the purchase with, while also paying for licensing, registration, and submitting to arrest and search of their property on-demand without so much as probable cause (never mind a warrant, the standard is "reasonable suspicion"), they will think it's "freedom" to commute back and forth just to earn enough to pay for "more lanes" in vain hope they'll spend less of their time in traffic "in the future."