"Why bother deterring the more-common low-effort risks if there are higher effort ways to thwart the deterrence?"
How often do muggers carry foil pockets even in first world countries? Certainly not in places where there's a mugging almost every week. Some way to track the device on its way to wherever they strip them off for parts would be helpful than not being to track it at all.
I don't think people would be fine with being unable to power any electronic device down at need, even if they're not the owner.
It feels like something that needs to be as easy as possible, for safety reasons if not anything else.
Now what I'd like to see is an extension of their protocol that is used to locate iPhones that would also let them accept a "remote wipe" command, even when powered down.
You can definitely block AirPlane mode without a passcode on iOS. I disabled the access to the control center when the iPhone is locked. Therefore thieves won’t be able to do so.
Theft Detection Lock uses AI, your device's motion sensors, Wi-Fi and Bluetooth to detect if someone unexpectedly takes your device and runs away. If Theft Detection Lock detects that your device is taken from you, it automatically locks your device's screen to protect its content.
Slight mitigation to this is you can add an automation via the Shortcuts app to be triggered when airplane mode is enabled, and set the actions to immediately lock your device and disable airplane mode
Downside is that you need to manually disable the automation if you actually wish to use airplane mode (and also remember to re-enable it when done)
I've set two automations: 1) When airplane mode is activated, lock the screen. 2) When airplane mode is activated, turn it back off. That'll give me the most opportunity to either track it and/or lock it down remotely.
I can remember to disable the shortcut whenever I fly and need to enable it.
If they pop my SIM (my provider doesn't use eSIMs...) then there's a PIN on it to prevent use in another device.