Lane configuration at traffic signals are dependent of the operation of the signal. We have been asked this question before and there is a reason for the current design.
Crossville/SR 92 essentially runs east and west. Mansell Road and the bank driveway are north/south. When E-W stops, N-S vehicles can go at the same time. If we were to make the southbound through lane a permissive left (making two left-turn lanes) it would be in conflict with the simultaneous northbound movement out of the bank driveway.
In order to allow this we would have to separate the southbound movement from the northbound movement. This is called split phasing. We only do this in rare circumstances as it takes valuable time out of the heavier SR 92 main line through moment and would result in less efficient operation at the traffic signal. Additionally since this is a State Route, Georgia DOT would not allow it.

Thanks for fixing this request!