Population growth seems to me to be a major problem. Roads that worked perfectly well 40 years ago are just inadequate today. Roads that were built new 40 years ago, I mean.
Cities once had housing around workplaces, so a trip to work was easy, and often we went afoot, but now cities are a conglomeration of small towns and suburbs around that original city, and the original housing IN that city is mostly gone, for working stiffs anyway, and no provision has been left for new roading to be built from the suburbs where those punters CAN afford a home. And public transport between suburbs is dismally inadequate, so you can only use it to go downtown. Downtown where the only work is for what we call 'suits.'