This is quite a stretch. Uber is eliminating drunk driving fatalities now? Those same people couldn't have called a cab before Uber existed?
Speaking for myself, I take Uber/Lyft regularly but would have never even considered attempting to call a cab and dealing with the cost/uncertainty inherent to that. I'd much rather not spend an hour waiting outside for a cab that ultimately decides not to show up. Rather than deal with cabs, I would simply just not have had a drink if I didn't have a designated driver.
I can remember a specific example several years ago in Nashville (which is quickly becoming a big city) where after waiting for 15+ minutes downtown I had to start calling companies telling them to send a car to my corner.
Before Uber came to Chattanooga (a decent-sized city) calling a taxi wasn't even a viable option unless it was for a scheduled 4AM airport pickup.