[simondotau]

I realise that you're talking about global Governments, but when it comes to the United States, Government pressure cannot compel Apple to expand the on-device searching because that would be an unequivocal violation of the 4th Amendment of the US Constitution. Because it is a search of your private property compelled by the Government.

(After a photo is uploaded to a cloud service, a search of photos stored on servers doesn't enjoy the same 4A protection as this falls under the so-called "third party doctrine".)

(Apple searching for CSAM is also not a 4A violation because it was Apple's free choice as a private company to do so, and you will have agreed to it as part of the Terms of Service of the next version of iOS.)