The Oppression trait under the Totalitarianism ideology says that "Faction benefits increased by 50%" (first screen snapshot below).  The second screen snapshot shows the faction benefits before adding the Oppression trait and the third screen snapshot shows the faction benefits after adding the Oppression trait.  While the benefits are increased, they are not increased by 50%.  From a player's perspective, if you say the faction benefits will be increased by 50% then I expect them to be increased by 50%.  There may be some perfectly rational explanation for how the actual increase is calculated and I am not arguing about that.  My point is that the game should do what it says it will do from a player's perspective.