I hadn't taped the crash episode so I couldn't be certain, but now I can.When Rob and Amber came upon the accident site, there was a cameraman kneeling near the road, away from the accident, with his back to the accident, filming cars as they approached.
Seeing that, I wouldn't have given stopping or slowing down a second thought.
IT's clear that we don't see everything that happens, but even based on what we did see the decision is obvious.