Let's debate honestly about what we think is acceptable. I honestly don't know, but I think perfect security is a mathematical inevitability, so I guess I'm more on the side of figuring out how to live with it.
No.
Do you know how the police normally operate? There is a victim who comes to the police and says "these people committed a crime" and the police go investigate. They get a warrant based on the victim's testimony/evidence. They plant a bug in the suspect's home/office/car. They send undercover officers to infiltrate the organization. They interview witnesses and find other victims.
All of which can be done regardless of whether they can read your iPhone, which people didn't even have 15 years ago. And a video bug can capture you entering your PIN into your iPhone before they arrest you and confiscate it, so there is also that.
I mean, why draw the line here? Bugs and taps were new at one point. Why not say "police used to get things done without these newfangled spy devices, so why should we allow it now?" I would say a bug or tap is actually very invasive, but as long as a warrant is required, it doesn't seem so bad.
The difference with an iPhone is not that it hides criminal activity but that it records it to begin with. There was no default recording of the content of communications. What loss have the police suffered that the information is now stored but unreadable when it was previously not stored at all?
> I mean, why draw the line here?
Because there is a difference between the police being allowed to do something and everyone else being obligated to facilitate it.