I don't know how it is in other countries, but here in Japan, when you buy a phone in a mobile carrier shop, they set it up for you, which means any on-boarding that exists on the phone OS is skipped entirely.
iOS setup is personalized so your carrier shouldn’t be setting up anything for you. E.g when you startup you need to setup your faceid and other personal info, that a carrier can’t setup. The most a carrier can do is pre-configure the phone with a specific activation.
If they’re skipping that for users then they’re breaking the entire flow for transferring data , setting up payment and authentication etc…
I don't know how it is in other countries, but here in Japan, when you buy a phone in a mobile carrier shop, they set it up for you, which means any on-boarding that exists on the phone OS is skipped entirely.