Title is self explanatory. In the factiondefs.xml there is a list of 8 entries for AI priority. I will give the terran entry in this field as an example.
<AICategoryWeight>
<Military>15</Military>
<Growth>10</Growth>
<Tech>20</Tech>
<Diplomacy>15</Diplomacy>
<Expansion>20</Expansion>
<Wealth>10</Wealth>
<Influence>5</Influence>
<Fortification>5</Fortification>
</AICategoryWeight>
This field corresponds almost exactly with the in game AI priorities that you can see in the race editor. With the exception that in game there are 9 priorities. Logistics is missing from the XML.
To test this, I revalued all the entries and inserted logistics with a value which would put it in third priority. This change is reflected in the ingame editor.
I believe this explains why the base races do not research logistics with any reliability. My intent is to test this in the next hour or so to confirm that the break down in logistical research is a result of this missing entry and not a result of hardcoded decision making. I will update the thread when I have results to report on this.
(Edit) Looking at a save game with FOW disabled, it's very clear that logistical research is just luck at the moment with the current races when they have a 0 priority in logistics. There is some research going on, but not always. Current game I am looking at, 157 turns, Altarians have a 30 cap. Terrans 30. Krynn which is one of the most powerful factions is at 20, and the Iridium Corporation is sitting at 10.