This is a common carbrain argument
“I already pay the gas tax”
The problem is that it’s false.
In a recent study, researchers Stefan Gössling, Jessica Kees, and Todd Litman calculated the social costs of driving. They found that the social cost is about 30-40% higher than what car owners are actually paying
https://www.sciencedirect.com/science/article/pii/S0921800921003943?via=ihub
That cost is paid by non-drivers.
I remember driving out West in Arizona and New Mexico, the Interstate paralleling the train tracks. There were at best a handful of trucks on the road, while I’d see these mile-long trains out of the ports of LA or Long Beach every half hour, or less.
I also walked on a section of the original Route 66 that they’ve preserved in Flagstaff. The U.S. numbered highway system was conceived and built for private cars. As was the Interstate Highway System.
IME, “roads are for freight” is one of those things people just say because it sounds good, and they want it to be true at some level, even though it’s so obviously false if you just look around. (I was out there to buy a boat, and buying a tow vehicle and driving it myself was much cheaper than any LTL freight service.)