There are several places where car manufacturers place the radio antenna. Some very cheap cars place it at the top of the windshield, inside the car. Other cheap cars place it in the front section of the roof. Older cars had antennas near the boot/trunk. The majority nowadays place it in the rear section of the roof. Why is that? What is the advantage/disadvantage of each of these positions?
A primary factor in antenna design is the consideration of the ground plane. For radio antennae, one desires an omnidirectional pattern, that is, the ability to receive signals equally from all directions.
One can argue aesthetics against placing the antenna in the direct center of the roof (if that's also the center of the overall metal area of the vehicle) which leaves placing it at the rear.
It's likely to be more directional when placed fully aft, as if often the case with an SUV or other boxy vehicle, but the aesthetics come into play again. It would look fairly strange placed one- or two-thirds back from the leading edge of the roof.
Additional considerations involve the production process. How easily can a robot or worker guide the antenna lead from the dash/radio to the intended mounting location.
With many antennae being designed to accept satellite radio reception, it's likely to be a small factor, as the ground plane for such frequencies will be a small metal "patch" internal to the antenna and oriented for reception from the sky.