That isn’t an original idea. See for example https://www.vabike.org/vehicle-weight-and-road-damage/ (2009)
Also, if in Google “50 ton 5-axle truck” I get trucks that I rarely see on roads in Europe. Reading https://www.jpisla.es/resources/Download+JPIsla+20130106+Pes..., that’s because t most countries don’t allow them on roads.
Add an empty trailer and you get 35 tons (5 axles, 2400 units of damage). US max allowed is 80 tons, for a whopping 65,536 units of damage.
I don't know how full they are, but I see 5-axle tractor-trailers on highways all the time in the US, and also locally doing last-mile deliveries to larger businesses like supermarkets and home improvement stores.
I guess the differences in allowed weights might account for why US roads are often in worse shape than many in Europe, though I assume vastly different maintenance schedules play a large part as well.
[0] https://www.tcsfuel.com/blog/truck-weight-classification/
Max US ordinary large truck loading is 80k lbs, or 40 tons.
(Source, I trained as a civil engineer. Units in us practice were all over the place, but kip was generally the one that got used the most.)
https://en.wikipedia.org/wiki/Large_goods_vehicle
https://assets.publishing.service.gov.uk/government/uploads/...
The principle that shifting traffic from cars to bikes saves money for the government is a sound one. There'll always be a need for cars for some things -- probably not gonna have ambulance bikes, and of course deliveries for anything big needs a car/truck -- but you can certainly reduce the need. Especially with ebikes making biking more convenient and accessible.
The point isn't to individually shame unwilling people out of their cars. The point is to make biking a real, viable transportation mode for short/medium distance trips for most people in urban or suburban areas. It's entirely possible to do this with the right infrastructure.
Once you do that, people will choose biking of their own accord, because it makes sense.