Structurally speaking, what mechanism prevents Amazon from being able to access RDS-managed customer data that doesn't prevent Palantir from doing the same? As

Structurally speaking, what mechanism prevents Amazon from being able to access RDS-managed customer data that doesn't prevent Palantir from doing the same? As far as I'm aware, Palantir doesn't claim to share data between its customers. It works with governments all over the world — ostensibly this means that either Palantir agrees to not share its customers data with other customers, or every government is implicitly consenting to their citizens' data being accessed by every other government.