I don't think surge pricing affects the number of drivers in the immediate moment. I think the effect of surge pricing is meaningful over the long term though.

I don't think surge pricing affects the number of drivers in the immediate moment. I think the effect of surge pricing is meaningful over the long term though. Drivers who could be pursuing other methods of making money will choose to drive for Uber instead of doing something else, like driving a normal taxi. Surge pricing also has the affect of reducing the number of people calling Uber. This ensures the people who have the highest ability to pay continue to view your service as a fast, reliable and comfortable alternative to the ever-present taxi. In this sense, surge pricing effectively creates tiered service automatically.