You're post makes a whole lot of assumptions about ridesharing.

1. Uber drivers are compensated sufficiently for their time and expenses (research has shown this isn't true, Uber drivers scrape by just like cabbies)

2. That a consumer's time is more valuable than having public transportation available to everyone (Ridesharing > Buses/bike shares/etc)

3. That expensive rail is one of the only options.

The solution is a mix of buses, bicycle sharing, and electric self-driving cars. How we get there is the tricky part.