An organization representing independent taxi drivers sent a petition to the Taxi and Limousine Commission (TLC) to force Uber to offer passengers the option to tip their drivers.

“Tips are drivers’ bread and butter, and traditionally account for as much as a quarter of their earnings. Uber’s refusal to give passengers a tipping option has effectively slashed driver pay, making it all the more difficult for drivers to support their families in one of the most expensive cities in America,â€ said Jim Conigliaro Jr., founder of the Independent Drivers Guild, in a press release.

“Uber has a reputation for skirting rules and industry standards, but depriving drivers of the opportunity to earn tips is bad business. The fact that they are denying drivers the ability to earn tips at the same time as the company has cut pay and nearly tripled their take of driver pay is beyond the pale. It’s time to hold Uber to the same standard as taxis and the rest of the service industry and require a tipping option.â€

Nearly 50,000 Uber drivers are represented by the Independent Drivers Guild. The TLC has 60 days to respond to the request.

Uber is notoriously stubborn about its refusal to allow a tipping option in its app. That lack of a tipping feature has led to “passenger confusion and resulted in drastic reductions in tipping income, which has long made up a substantial portion of driver earnings,â€ according to the Guild.

The organization, which was launched last May, has taken credit for several victories including pressuring Uber CEO Travis Kalanick to step down from President’s Trump economic advisory council after Trump’s Executive Order banning Muslims from seven countries from immigrating to the U.S.

The Guild also negotiated discounts for drivers on insurance and other expenses drivers face, such as legal assistance fighting unfair tickets, mobile phone plans, and tax preparation services.