Public transit tends to be a somewhat politicized issue, I’d guess mostly because areas that need large investment are usually already suburban and their tax base doesn’t see the utility, and on the flip side addressing deferred maintenance let alone expansion isn’t necessarily exciting. Areas that have it already should be improving their systems more aggressively, and taking a page from Tokyo’s book.
If we want to see why public transit is so often mediocre, consider the brand of most public transit in the marketplace. Does it have a coherent brand in a given area? Is the price competitive? Is ticketing frictionless? Is it fun to ride?
Cities and regions should be thinking in terms of competition with private vehicle ownership and the brands developed by the manufacturers.