You can; the thief just didn’t get to do that because they were busy getting away in a non-conspicuous way.

But even turned off, “Find my” stays active these days (although you can no longer make it ring, I believe).

That option can be disabled by turning off "Find My network" such that the phone will be off and radio silent. With it on, it will continue to beacon until the battery reaches the final BMS low voltage point.

but turning it off requires your password/PIN.

Yeah but turning on airplane mode does disable find my

It doesn’t, as far as I know (or rather, it might turn off the ability to ping the phone, but passive Bluetooth/Find my cloud location should still work).

And even if it does, turning on Airplane mode is not possible anymore for a locked phone.

Disassemble and remove the battery. I can do this in about 1-2 minutes, others more skilled can do it in <30 seconds.

And then? You can not turn it on again, without also activating the beacon.

I wonder if stolen iphones have any value except for hardware parts.

1) Faraday cage.

2) If the thief knows or can guess your passcode, you are screwed, because they can take over your iCloud: https://www.macrumors.com/2023/04/19/apple-responds-to-iphon...

In Brazil the thief menaces you till you give him your password

they don't have many guesses to do that, how would they know the code given almost everyone unlocks via camera?

Read the link? Apple requires you to enter the passcode every now and then, and thieves exploit when that happens in public.

Didn't iphones start to have DRM on the individual components?

Yeah I also wonder what a thief would do with it? Maybe the recycle value is enough for her? Or she gets it to a store where they don't check and recycle parts?

While walking and without alerting the person you just bumped into to the fact that you just took their phone? More realistically, a well-prepared/tech-savvy thief could just drop the phone into a Faraday bag in their backpack/pocket, or alternatively just turn off the phone!

Fortunately, the one that my friend encountered didn't do any of that.