If UN or another international body like Interpol suddenly grew the courage to do it planetwide, I'd be the first to volunteer.

You can volunteer installing CCTV in all your rooms, including toilet, and regularly send the footage to the police station. However, let us, normal people, to be excluded from this dystopian madness.

Considered, sure. But easily rejected. Let’s be grownups here.

Yes, indeed, let's! Grownups recognize that strip searches are unwarranted in this and most other cases, be they physical OR digital...

And certainly you've heard of software bugs. You do not think that a small one like "accidentally" "forgetting" to check that a photo had been synced cannot happen, and an "accidental" scan of ALL photos couldn't possibly happen in any situation no matter what bug/corruption/etc? Surely you'll share with the class where YOU hire infallible programmers.

An accidental strip search is a strip search nonetheless.

Luckily, this can all be solved by NOT writing such code. Ever.

You must surely realise that there’s a fairly large difference between being strip-searched and having a hash computed on one of your photos that you’re uploading to iCloud.

Don't see any difference. In both cases your private property forcibly accessed without any reason to suspect you, but rather out of preventive reasons.

You must surely realize that slippery slopes exist. And as soon as adversarial code exists in your device, it will only expand.

Reference: history of literally every dictatorship includes many "reasonable" expansions of power in the name of security/safety/etc...

Yes, but I think you’d agree that each slippery slope has a certain degree of probability.

The slippery slope from Apple checking image hashes to hourly strip-searches seems rather unlikely, which makes your analogy unhelpful.