Cows are not as leggy.
I am not clear if Art's cows were laying down on the road or standing either.

People have mentioned how hard moose are to see and moose are counter colour camoflaged.
Even in the headlights they tend to match the look of the road because they are usually darker on top than they are on the legs.
At your eye height the dark body just looks like the rest of the night does and the legs look like the headlight glare reflecting back off the road.
In the fog, rain or snow it is worse

One winter night I counted 27 moose on the road between Wawa and Timmons.

Moose are big enough to kill transport trucks.

Anyhow, sane folks do not hunt large animals with their motor vehicles.
Slow down at night please.