That’s not so clear cut. The alternative to Uber is not just staying home or riding a bike, at times it’s driving your own car and circling for 30 minutes trying to find a parking spot.
Comparing the number of cars in NYC/DC/etc garages vs on street parking people are still mostly using company provided / reimbursed the garages down town. So, while some people in some areas may spend time circling, across all trips average circling time is minimal.