I suspect there are any number of factors that could account for the abundance or lack of turkeys in a particular location. Out here in some arid parts of the west, the availability of water is most certainly a determining factor. If there is not a reliable source of surface water for turkeys to be able to drink, there is a high probability that there will be few, if any, turkeys in the area, even if the surrounding habitat appears to be favorable. Conversely, in areas with a good distribution of water sources, turkey numbers are often good and are found throughout those area.
Having said the above, I have also hunted areas out here which appeared to have all the ingredients to support good turkey populations but have been pretty devoid of birds. In those areas, the reasons for the lack of turkeys are not at all clear to me.