Specific Class abilities as faction trait

There are some traits that provide an ability to a specific class, such as the Biest trait Elevated Aristocracy , which gives +2 Command to a single class, and Humanoid Heroic Nobility (+1Cmd for L3-5, and Squad Size 1 for L1). Do classes not benefitting from this still pay for the trait cost? In the former case, would the classes getting the Command increase be the only ones to pay, and in the latter do L2 classes not pay, or do all of your classes have to pay regardless of whether they are affected?