I’m pretty sure lots of mail gets x-rayed, perhaps even more looking for malicious packages or substances.
I agree that data content scanning is more invasive than physical scanning. It was an intentionally simplistic example not meant to defend Apple.
Parcels, maybe. I’d bet it’s a tiny percentage though.
I doubt the entire world has enough X-ray machines to scan even a vanishingly small percentage of the envelopes the postal service delivers every day.
That is a totally bogus comparison.
The post office 100% does NOT can the content of every piece mail they handle.
Not even close to the same scenario as Apple/governments being able to continually and silently check your phone/photo library for images on their watch list.