California law treats common carriers, including public transit agencies like MTA, differently from ordinary drivers. A common carrier must exercise the utmost care and diligence for safety, and this heightened duty extends to pedestrians and other motorists near the bus, as set out in California Civil Code section 2100. MTA cannot defend a case by treating its driver as just another driver on the road. MTA, the public entity employer, was held responsible for its driver's conduct under respondeat superior and Government Code section 815.2, which makes a public entity vicariously liable for the negligent acts of employees acting within the scope of employment. The driver was on duty, on her assigned route, at the time of the collision.