The catch? In most cities examined in the report, those benefits only extend to low- and middle-class residents. (In Johannesburg, the poorest residents did not use BRT).

“Since the dominant benefit is travel time savings,” the study’s authors wrote, “the majority of benefits tend to accrue to the strata most represented by BRT users — typically lower- and middle-income.”

While it’s great to have a system that improves transportation access for the majority of a city’s population, BRT’s mass appeal could — ironically — be a political concern that prevents its adoption, at least in the U.S. As Alex Pareene wrote in Salon, public transit often suffers because politicians and donors rarely rely on it. The results show in the states, whose existing BRT systems lag behind those in cities around the world.

Even in densely populated and traditionally liberal cities like New York and Minneapolis, politicians neglect transit. And “because they don’t know or interact with or receive checks from people who rely on it every day, there’s almost no hope for cheap, efficient mass transit options anywhere,” Pareene wrote.