RT is more of a playground and a place to test things, so it naturally has more players and more events. Not to mention you get 1000`s of turns a day vs. a few hundred.
Some reasons we don`t do TB events:
-Giving away a 50k C3 in RT is nothing, while giving away a 50k C3 in Slow, for example, would high imbalance the game.
-Inactivity. The very nature of TB servers make them impossible to host an event. The players log on at very random intervals once every day or so to spend turns. In RT, there`s always 20 or so players on to fight over rewards.
There are others but those are the reasons that come to mind atm.