Funny, but on a recent run on I-25, my headlight wigwag just happened to coodrinate with the hi-lo I was using in heavy traffic moving at 5 mph.
Yes, you could coordinate sound and lights.
But why spend money and complicate things to do it?
Thanks Q for your interesting observation.
Maybe due to that partially reflective feature in mirrors when flipping the mirror up.
(My former Japanese girlfriend had been driving for 20 years before
learning from me that auto mirrors had that feature.)