Amazon's external-facing security seems robust, but most places I've worked have given a lot of trust to people on the inside. I've worked at places where all developers get read access to all databases - and managers who are former developers usually retain that access.

Amazon might have good internal security procedures - but this stuff can't be audited effectively, we can only take amazon's word for it. Taking their word for it, with the security of all your customers' data, is a big ask.