The main concern seems to be that people are afraid that other governments can use this technology to have iPhones scan for other types of images. (The "Tank Man" photo is often given as an example)

Apple say they won't do that, but it's perfectly healthy to not trust Apple on that aspect.

But the fact that they're scanning for CSAM images doesn't change the above in any way. If they back down and stop scanning for CSAM images, that won't have any effect on the above. The governments can still pressure them to add this to their phones. Or even worse. Maybe they have.

It's like people disabling exposure notifications because they don't trust Apple. If that's the case, why do you trust the toggle to actually do anything?

You either trust Apple that they won't bow down to pressure, or you don't, in which case, buy a phone from a company that you trust more.

As someone said on a podcast recently, this isn't a technological problem, it's a government problem. The solution is to vote, not to change your mobile phone.