SAN FRANCISCO -- Uber drivers are pushing for a level playing field in the transportation market.
According to CNET, drivers are asking the app's San Francisco-based creators to add a gratuity feature.
Right now, if an Uber rider wants to tip, it has to be with cash.
Drivers say that's not happening often. But their competitors with Lyft and cabbies are collecting.
An online petition for the tip feature has close to 14,000 signatures.