The buses reportedly have corrupt owners, and are driven by untrained and over worked drivers. "They drive for 12 to 14 hours a day. ... no system of training, the buses are not maintained properly" says Rohit Baluja, president of the Institute of Road Traffic Education, a non-profit road safety organization. The Gate says a quarter of the buses are owned by police and family members of prominent politicians, and owners bribe the traffic cops to turn a blind eye to infractions.
While there are protests and calls for regulation, even family of the victims still take the buses because of the very low 25 cent fare.
[Source: BBC News, SF Gate]