If AWS were really aggregating customer's data stored in AWS' platform, I think we'd be seeing a lot more about it in the news. And there would be a lot more than just Walmart advocating against its use.

This is why this comparison doesn't make sense. Google Analytics is a 3rd party service where you have no control at all of your data. You put a script of your app, and then you basically funnel data to them. That's it.

Using Pinpoint, in this case, is the equivalent of using EC2 and S3. You can control the flow and the lifecycle of data (deleting data forever, for example).

You should be able to trust that your customer data is safe there, otherwise, why use AWS at all? or better yet, why use any public cloud infrastructure provider at all?

If you're concerned about that, you probably should build your own self-managed server infrastructure.