Most people aren’t trans, but anti-trans legislation still affects them. It doesn’t really matter who it affects more, because it is meant as a culture war, but also as a hate tactic to bully people. How do you check that someone is transgender? You really can’t. You could claim they are dressing a certain way that doesn’t match. You could claim they look like they have more of a hormonal type. You could claim they are acting a way that doesn’t match their assigned gender at birth.
But that’s the point. You can pick and choose who to apply this to.