Cognitive behavioral therapy is a more standardized and measurable type of therapy than things like interpersonal therapy or problem solving therapy or psychodynamic therapy, and thus it is easier to study in a controlled setting. So there are more studies of CBT than other types of therapy just because it is easier to study

I don't have references offhand but there are controlled studies that show benefit of other types of therapy

Overall all though, all psychotherapy studies are messy

The idea you're raising, the differential efficacy of CBT, is a myth originating in the politics of psychiatry and psychology, especially in the 70s and 80s. There is abundant evidence for psychotherapy, but no evidence that any type is better than any other, especially when you control for publication bias. It's the "common factors" phenomenon, where therapies that have some baseline characteristics all do about equal. It's well documented and known, but people in the field often pretend it doesn't exist.

There may be some tendency for some therapies to work better for some people more than others, but identifying how to match people to therapies hasn't been demonstrated well or replicably.