I said trains, not subways. I said "majority of miles" not "to the store". The tax is the same on goods shipped by other methods, so you can't count it as somehow balancing out the economic distortions caused by subsidizing trucking infrastructure.

The problem is that non-truck solutions cost more relatively due to government intervention, messing up the market's ability to find more optimal solutions. This one is simple, it doesn't even require you to think about carbon taxes to do the math. It's direct costs, subsidies to a certain technology. Don't pick winners and losers, create an environment where capitalism can function and find the actual best solutions.

Charge trucks for damage they directly cause to roads. Simple.