We do. But it’s a super regressive tax. Lots of very poor people depend on a bad MPG car to get to work and live.

that's a different problem. US cities used to have good publhc transport, but the urvanization policies since 50s is car-centric. plus, because of the American cars having huge engines they have bad MPG. The current situation US is in is nothing to do with the tax regime.

If you subsidize polluting life-styles, you'll get pollution.

You think the rich suffer from pollution and car dependency? It's not at all clear that taxing gas will lead to worse outcomes for the poor. It's entirely clear that subsidizing pollution from the poor will lead to worse outcomes for the planet.

What isn’t clear about the fact that increasing commuting costs for those living paycheck to paycheck leads to a worse outcome?

Because you're only considering first-order effects. Behaviors, markets, and systems will evolve around the new rules. Public transit could improve. People could trade in SUVs for hybrid sedans. People could carpool. People could bike. People could walk. Corner stores could re-open. People could demand zoning changes, instead of fighting every nearby development.