The South Eastern Pennsylvania Transit Authority uses M and F stickers on weekly and monthly passes to keep riders from sharing passes, spokeswoman Jerri Williams told The Philadelphia Inquirer.
Activist Kathy Padilla isn't buying it, since "any two women or two men can share passes."
Other major transit agencies do not identify customers by gender. But in Philadelphia, each SEPTA ticket seller judges whether the buyer looks male or female, and if a driver or conductor disagrees, the pass can be confiscated.
Riders Against Gender Exclusion has gathered testimony from about 20 transgender riders who said they were questioned and publicly ridiculed by drivers.
SEPTA says that as a state agency, it is not bound by the city's bias laws. It also says the issue will be moot when refillable cards come in that will not have gender designations.
RAGE is calling for a Bill of Rights to protect all riders.
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