Why can an iPhone be switched off the it's locked without asking for passcode?

tanmay22 wrote:

Iphones are known for their security features, But why it can be switched/power off even when it's locked without asking for face Id or passcode.

Because requiring a passcode to turn the phone off would create more problems than it would solve. It would make many kinds of troubleshooting impossible. And, thieves don't need to turn a phone off to make it unfindable. All they have to do is put it in a container that radio waves can't penetrate (e.g. Faraday bags) or wait until the battery goes dead.

Find My... is not a theft prevention feature. It's a way to find a lost phone.

If a thief ever gets a hold of my phone, I would hope that he would turn it off. That would prevent him from trying to get any of the data on my phone.

Let's be realistic. If a phone is stolen, you are not going to get it back. The Find My feature is helpful when you may have left the phone at a friend's house, a restaurant, or your workplace.