After 10 years of open competition, it can be reasonably concluded that Apple's products must offer some kind of extra value that others can't. The ease of use of Facetime, the convenience of getting a replacement device at a local Apple Store immediately and restoring with iCloud, the ability to send SMS/MMS/iMessage from macOS. And biggest of all, no worries about bloat ware and malware.

Branding alone won't work in the long term, you have to also provide a superior experience, which obviously apple's ecosystem does. Similarly, Tesla has the branding right now, and will enjoy their premium if they continue to deliver quality. But if they don't, and other manufacturers step up, then people will gradually buy something else.