Here in Little Rock, there are a handful of lights mounted similarly "too high". One I'm thinking of is actually mounted
above the horizontal arm on the mastarm pole, which extends several extra feet upwards for it. They are installed as 'extra' heads beyond the normal full compliment (at normal heights), where the road approaching the intersection is on a hill or curve (or both), and thus serve to help motorists be better aware of the state of the intersection as they reach it.

EDIT, to add GoogleMap image. (if I'm doing it right) Notice the far right-hand signal above the mastarm, which is facing the "wrong" direction than the others.
https://maps.google.com/maps?q=Financia ... e31prV9EEA