It's easy to blame 'falling asleep' when it cannot ever be proved. Accidents usually have more than one cause, This Rama 2 is obviously a fast highway, and yet we have a fully laden motorcycle/sidecar pottering at what cannot have been more than 40 to 50kph. Did it have any rear lighting or bright reflecting surfaces? Where the riders wearing bright clothing?
A following vehicle, travelling at high speed, as this Fortuner clearly was could easily have failed to see it in time.
I wonder how thoroughly these accidents are really investigated.