It isn’t only about the animals, dangerous chaos could have resulted from them getting hit by cars.
I have seen a CHP car do the tactic to close down Interstate 8 and it was impressive, although in this case I don’t know how it would have been done since the ducks were already there and would have required a quick on the spot shutdown rather than the increasingly wider all lanes weaving and decreasing speed maneuver that I had witnessed.
Actually sometimes it’s better to let some ducks get flattened rather than causing a multi car collision with human injuries.
A while back some idiot stopped in the middle of a major thoroughfare to “rescue” a turtle. He almost became road pizza himself when he jumped out of his car.
It’s one thing to slow down on a little used road, totally another during rush hour.
It’s just an animal.