When the wealthy[1] can opt out of having to use public services, those public services tend to be crap.
When the wealthy are forced to use public services, all of a sudden, they become interested and politically engaged in improving them.
Uber doesn't drive improvements in transit in this sense - it starves it of political capital.
The best transit services are ones which are used by a wide swathe of the public.
[1] If you are regularly paying $6-30 for a one-way taxi commute, you are either wealthy, really money-foolish, or a truly special case.