Because of the fiction of why Factions happened.
Lord British and Nystul created Trammel, to escape from the unstoppable armies of Minax.
The new Trammel was under the jurisdiction of Lord British, and after he left (twice) a ruling body called either the RUling COuncil, Royal Council, or High Council.
After Trammel was created, the old land, now called Felucca, was devastated.
Lord British and Nystul blamed Minax. The Council of Mages, under the leadership of Anon, blamed the magic Lord British used to create Minax.
Minax, interestingly enough, backed up the Council of Mages' claim that LB and Nystul were at fault.
The Shadowlords appeared out of nowhere basically, as a cult devoted to 3 legendary, wraithlike demonic entities. They had power without having a clear source of it....Until now of course...
Start here and click around in the UO Guide.
http://www.uoguide.com/Factions
Those of us (at least some of us anyway) writing that didn't know as much about the systems of Factions at the time, so we strove to give at least sketches of the background.
But yeah, that's why no Trammel. Because the fiction explaining why Factions is there at all is Fel-specific.
-Galen's player