That’s completely untrue. Yes we spend more on vehicles than transit. But way more people drive than use transit. There is not even a comparison.
In 2016 federal and state spending on road, transit, and water infrastructure was $416 billion: https://www.bidnet.com/resources/business-insights/us-govern.... Water is about 1/3 of that, leaving $276 billion for transportation. Spending on transit was $65 billion, or 1/4 the transportation spend.
Transit, however, accounts for just 5% of commutes: https://www.bts.gov/content/commute-mode-share-2015. 85% is driving alone or in a car pool. So we spend 3x as much on road infrastructure, but 17x as many people drive to work as take transit.
If you run the numbers on a cents of subsidy per passenger mile basis, busses and subway trains come out to $0.50+ per passenger mile. Roads are just $0.02 per passenger mile. Even adding in CO2 footprint and pollution (assuming that cars are all ICE) puts you at about $0.25.
Transit is incredibly expensive.