Go through a security review. It not as simple as just saying "we outsource that so we have no idea what they do or how they manage the data". It is disingenuous to claim that people can just outsource the whole problem and not care.

This would be part of the responsibility of the cloud managers, which need to be hired, paid and trained, on top of the cost of paying the cloud providers. There is no free lunch.

I am responsible for security reviews. I never claimed it was that simple, nor that there was free lunch. I said it is easier to outsource it than to handle it yourself to an equal level of what a cloud provider is able to do, from a legal and operational perspective.