This is not true at all. Differential privacy works to counteract EXACTLY these types of attacks. There are some very basic proofs that the privacy guarantees o

This is not true at all. Differential privacy works to counteract EXACTLY these types of attacks. There are some very basic proofs that the privacy guarantees of a differential private release mechanism is not at all weakened by external data, such as what you've listed. Differential privacy attempts to minimize the risk of being a row in a database given that the attacker knows the values of every other row (and has whatever external data he wants).