SAN FRANCISCO Mask slackers will now have to provide photographic proof they're wearing a face covering before boarding an Uber. The mask verification rule expands upon a similar requirement that Uber imposed on its drivers in May to help reassure passengers worried about being exposed to the novel coronavirus (COVID-19) that has upended society. The requirement will roll out in the U.S. and Canada later this month before coming to other parts of the world. The additional safety measures are part of Uber's ongoing efforts to rebuild a service that has seen ridership plunge this year. The adverse conditions caused the number of trips on Uber during its most recent quarter to plunge by 56% from the previous year.