You’re not getting it. If gas tax receipts drop 5% this year, raise the rates 5% next year to keep the gas tax *revenue* flat. Roads are paid for by the people still driving gas vehicles - there will just be fewer and fewer of them.
All I read is “Wouldn’t it be horrible if the externalities of gasoline had to be paid by the people using it rather than continuing to be subsidized by society?”
But this isn't about the externalities of gasoline, it's about the externalities of driving.