Automotive applications are different in that they're inordinately concerned with the appearance of reflections, especially in areas such as the appearance of the headlights. This makes non-raytraced approaches substantially less valuable in the design process. They really want to know what the shiny bits will look like ahead of time.

Raytracing still suffers form the performance implications of incoherent memory accesses patterns for non-primary rays, but when you want physically correct reflections and shadowing to fall out of the rendering architecture naturally, an implementation of ray tracing in hardware starts to look like a pretty spiffy idea.

Are there other fields that require physically correct models for reflections, etc? None spring to mind for me right away.