Because rural voters hate the idea of taxes at all and so when given the option they will literally vote to ban metro areas from taxing themselves as they just did in WA.
Why should rural voters pay for a city's transport system? At least city people do drive the rural roads between cities. (though I will agree they are overbuilt - but rural residents would be happy with cheap gravel roads they can afford)
> rural residents would be happy with cheap gravel roads they can afford
doubt it. regardless, federal government revenue goes disproportionately towards funding rural services and welfare, including many services that city residents don't use at all. federal funding of a city's transport system would still not shift that balance.
regardless, you missed the point of the parent comment.