[RedDevil]

While you can point solar cells towards the sun, that also raises the temperature in those panels making them less efficient. So part of the gain that should be had will be lost to reduced PV efficiency, especially on hot days.

Also, by placing the panels so that they do not ever face the sun straight on (like laying them almost flat at higher latitudes) allows for using smaller, cheaper inverters.
Laying them flat makes them catch more light in the hours just after sunrise and before sunset, especially in May to July.

It is hard to make a tracking system that does not expose the leads in some way.
A fixed roof mounted system can have the leads completely hidden under the panels.

All in all the cost, complexity and vulnerability of tracking systems usually outweighs the benefits. The cheaper panels will get, the less tracking systems make sense.