Flash photography. Probably blinded the driver for an instant.
A very bright flash would be necessary to photograph occupants in a car with tinted windows. a 1000 watt extended flash could easily blind a driver under the influence and at 75mph it would only take an instant to run into a pillor. I believe the paparrazzi on bikes caused the crash.
Or just headlights. i drive enough streets with speed-bumps, and hilly roads, to know that if you change the vertical angle from one vehicle to another, an ordinary headlight -- let alone one of those dangerously bright bluish halogens -- can look a lot like a blinding flash.
Probably a press photographer.