The current system of promoting cars above all other forms of transportation is more regressive than road pricing would be. Vehicle ownership and miles traveled are positively correlated with income. People with lower income are more likely to be reliant on underfunded public transportation that gets stuck in traffic (i.e. busses) caused by higher income drivers. Not to mention all the other externalities like pollution that cars cause, which disproportionately affect lower income neighborhoods.

So would you favor selling bread and other necessities for $0 by the same argument?