> special lanes or highways just for automated tractor trailers.

I know that there's last-mile advantages to this compared to what already exists, but god damn I just cannot get over the fact that we've just reinvented trains with a much larger environmental impact.

the way to think of these is as instantly reconfigurable trains. in an ideal market, an enterprising entreprenuer would be able to install tracks on the most used routes and lower costs (and emissions). but we've long succumbed to corruption and financialization in markets (note that if risk is priced properly, capital wouldn't need to evaluate opportunities deeply, but would rather take every NPV-positive project available, in order of expected returns, in a large and diverse enough portfolio to mitigate systemic risk).

but they’re cheaper at first

That is in my opinion the way to go with this, to either adapt the infrastructure to make it work or to at least separate the self driving traffic and the 'normal' traffic so the two won't interfere.