If we get there, then yes, the case can be made that there are strong reasons to go even further, and instead of subsidizing the auto transport system as we do today, shift that to subsidizing public transport instead.
But as an across the board principle, a level playing field would be such a step forward for public transport in the US, that I'm happy to focus on that at present. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.