Actually, most new utility scale PV in the US southwest is now using single axis tracking systems. The advantage here is that the power curve is flattened over the day, which both makes better use of the inverters and pushes more production into higher value time periods.
We are well past the point where tracking the sun was desirable. The apparatus that allows solar panels to track the sun is now much more expensive, especially when you consider the maintenance costs, than just using more static panels.