> There's no reason they couldn't do something similar/more modern with an iPhone and not have a security risk.
Of course there's a security risk. The security model of both the Macs and the iPhones have significantly improved. The hardware security models make this a difficult engineering task - and a dangerous one.
The modern day equivalent would be walking you through backing up to iCloud and restoring from iCloud. It’s not a security risk unless iCloud is one already.
What you describe sounds like a huge waste of everybody's time. Furthermore data migration on mobile devices mostly happens via iCloud these days - there's really no need to do that in store. It's part of the onboarding process whenever you boot up a new iOS device.
Pretty happy they don't do that anymore, then. It sounds terrible for security.