Hello 视讯
welcome to this Apple (user-to-user) Community!
Re: "Mobile phone security :
Why doesn't the iPhone require a passcode to be entered periodically ..."
Seems we can set up an iPhone according to our own requirements.
(Not everyone is able to enter a passcode, yet they can still use an iPhone.)
Apple provides articles online to assist in setting up an iPhone securely.
Apple support's online article: Setup basics - Apple Support explains how to set a passcode, and / or fingerprint / Face ID for security.
Eg: says:
"Set up Face ID or Touch ID
You can use Face ID (face recognition) or Touch ID (your fingerprint) to securely unlock your iPhone, sign in to many apps, and make purchases. For your security, Face ID and Touch ID data doesn’t leave your device and isn’t saved anywhere else.
Depending on your iPhone model, do one of the following:
- Set up Face ID: Go to Settings
> Face ID & Passcode, tap Set up Face ID, then follow the onscreen instructions. - Set up Touch ID: Go to Settings
> Touch ID & Passcode, tap Add a Fingerprint, then follow the onscreen instructions."
The above linked article also has much more set-up info.
You can also: Turn on Lock Screen features if you wish.
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Re: " ..... like Google does"
If you wish: You can Move from Android to iPhone or iPad - Apple Support
and / or
The article below (while not answering specifically) also does have a section devoted to moving from Android to iOS system. Turn on and set up iPhone - Apple Support
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Re: "Also, why doesn't the iPhone have an anti-theft lock?"
See how to: Use Stolen Device Protection on iPhone - Apple Support
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Re: "Why doesn't the OEM unlocking of the phone be required before flashing?"
Sorry I do not know : we are all Apple users, like yourself, in this community.
Also: we do not know how you have your iPhone set up.
You may wish to ask the original equipment manufacturer (OEM) : Apple: Support
or
The iPhone User-guide, is a useful resource.
(The Privacy and Security section has a great deal more information available ).
You can click the "Table of Contents" link on the welcome page to see what's available.
iPhone User Guide - Apple Support
All the best :-)