This is not limited to Apple. Top phone prices including Galaxy, Pixel etc have been steadily creeping upwards yearly starting from $500 and are now at $800-1000. Next year it could well be $1200 and in 3 years $1500.

Has the fundamental tech in the phones dramatically increased to justify this, not really.

The same applies to ultrabooks with low performance heavily throttled dual core chips, going from $700-800 to now $1500 plus. This applies to macbooks, dell xps, surface, hp and even lower cost alternatives like Asus.

There is a trend of sorts and it may well be rising income disparities means those at the top are not price sensitive and will pay $500 or $1500 with little qualms, and marketers are responding to the market.