But in any case, it's not clear that there is a lot of low hanging fruit in cutting down on private transit. Aside from a few outliers, most places with pretty great public transit still have a lot of private transit too. It has many use cases that public transit is unable to fill.
I suspect the best option for most suburban cities to reduce traffic and air pollution is to strongly incentivize employers to allow remote work when feasible.
It was privately-funded. It worked.
...until the automobile became more common and people stopped started driving cars instead. (The literal-conspiracy between General Motors and Firestone Tire didn't help, either.)
Here's a map from 1908: https://curtiswrightmaps.com/product/electric-railway-map-of...