Why isn't there are left turn arrow at Main and Pleasant?

After just witnessing yet another accident at the intersection of Main St. and Pleasant St. I ask again, “why isn’t there a green left turn arrow to Pleasant Street? Because of the delayed green going north on Main St. cars fly through the intersection to make the left turn. They have no idea the light for the oncoming traffic is about to or has changed. A light should be an easy fix. The cost of the accidents, both to the car owners for repairs and in insurance rates added to the potential loss of life at an intersection with multiple crosswalks should far outweigh the cost of a simple green arrow.