The agreements that Anthropic/OpenAI are pretty general and there’s a lot of use cases they don’t meet.
The list of compliance standards that AWS meets is so big they have a separate product just to deliver the compliance documents. They basically do everything imaginable.
It’s not just that. Oftentimes contracts stipulate that the client’s data can’t be transferred across certain boundaries. If you have signed such an agreement, even sending the data to a service on the same cloud provider but in a different region could be a huge compliance violation.