If you read the article, it helped ensure that no drivers were scamming them by creating repeat fake customer accounts to increase the payout bonus.

Demand mapping, driver supply allocation, more accurate surge pricing for the rest of us with the app...

They use location tracking even when you're not using the app to predict where the demand might be going and to get data for future products like the Uber Shuttle which runs fixed routes.

They could find them and convince them to reinstall.