Often it's because of secret government requirements. Compare https://en.wikipedia.org/wiki/Operation_Choke_Point https://en.wikipedia.org/wiki/Operation_Choke

Often it's because of secret government requirements. Compare https://en.wikipedia.org/wiki/Operation_Choke_Point https://en.wikipedia.org/wiki/Operation_Choke_Point . Somehow, it's forbidden for the government to oppress pornographers directly, but it's perfectly fine to impose legal sanctions on banks who maintain business relationships with them.