Green arrows have to go after 9 pm!

What is the point of green arrows coming on after the regular green light late at night? Anyone that was in the turn lane has already gone! It is just slowing down the light change for the other direction. As a topper - at Grant/CrayCroft where they are doing construction and reduced it to one lane in each direction with no left turns - the green arrow was still coming on! Unbelievable. Tucson is run sooooo poorly!