Clearly the dash cam used is sampling at a high enough rate to see them, but perhaps the Tesla isn't considering the a view of the road ahead across a wide enough period of time to see the hazard lights and understand the vehicle is potentially stationary and alerting drivers about a hazard.
A very naive FSD algorithm working only from the current frame (without looking at past frames) could certainly mess this up, but at what point do we accept this simply isn't fit for purpose - it can't avoid hitting a stationary vehicle, so what hope does it have with slowly moving and other edge cases?