Having a second/third/fourth platform that provides you with a positive probability of getting a ride while you have a wait time on your primary platform provides drivers better income per-minute/mile
For the record I have been stranded, messing around with drivers accepting then rejecting fares and then given up and taken either a street hail taxi or another app. I have even gulped down the fee for cancelling on a driver who drove off in the other direction for 20 minutes.