Not sure about DropBox, but AWS has alot of protections around what goes into S3. I have worked with them to address issues that come up in the service, and they couldn't access our data, even when we would have been fine with it. Had to copy it somewhere else for them.

All they could access was a service logs.

See https://aws.amazon.com/compliance/data-privacy-faq/

These are merely procedural rules (access keys don't grow on trees), which I'm sure Notion also has in place.

Not really.

There are protections in both cases. But they are different.

For instance, in the USA, there is no requirement that you have a mechanism to provide information stored at home to law enforcement, even under warrant/court order. If you have one, they can compel you to use it, but if you don't they have no remediation.

But a cloud provider is legally required to have that mechanism, and when order if they don't exercise it, they are punished. See: https://en.wikipedia.org/wiki/Stored_Communications_Act and https://en.wikipedia.org/wiki/CLOUD_Act.

The point of writing tests is to provide information, not prove correctness.

IE, a test is another way to explain what the developer of that test cared about, worried about, needed to verify of the code that is exercised.

Also, tests provide anothing built in consumer of the code, and all code with more consumers is better code, purely by surviving the stress.