If Amazon partnered with an actually independent European company, provided the software and training, and the independent company set it up and ran it; in case of dispute, Amazon could pull the branding and future software updates, but they wouldn't be able to access customer data without consent and assistance of the other company and the other company would be unlikely to provide that for requests that were contrary to European law. It would still be branded AWS for Europe, and nobody would doubt its independence.
This way, where it's all subsidiaries of Amazon can't be trusted though.
If Amazon partnered with an actually independent European company, provided the software and training, and the independent company set it up and ran it; in case of dispute, Amazon could pull the branding and future software updates, but they wouldn't be able to access customer data without consent and assistance of the other company and the other company would be unlikely to provide that for requests that were contrary to European law. It would still be branded AWS for Europe, and nobody would doubt its independence.
This way, where it's all subsidiaries of Amazon can't be trusted though.