Also potatoes are easy to grow! And ship in powdered form for cheap!

Trucks do “pay.” They move goods that are sold and taxed. Until subways start shipping things other than people, they can’t be considered the same as roads. A subway can move people around; roads also move significant goods around. Every single thing in a store has arrived by road for at least some portion of the journey. Farmers aren’t shipping carrots via tram.

What in the world are you talking about? Are you claiming that farmers never use trains to ship produce? Because that’s just patently false.

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.