"Rephrase your question to be about cars. I still won't be able to give you a good answer apart from "that's how markets work"."
As the saying has it, an Audi is a VW with a £4000 badge on front and a VW is a Skoda with a £3000 badge on front.
Now, being serious, it is a bit of a truism that the further you go up the scale the higher the markup becomes. There are many reasons for this. One is the greater financial risk if something expensive doesn't sell well. One is expectations of service. And then there is the fact that sales and marketing account for a lot more of the cost of high value items. Mercedes and BMW dealerships don't tend to be on trading estates; Apple stores are expensive to run.
When I was in that industry margins were extremely secret, but there was a suspicion that the margin over factory and R&D on a supermini was a few percent - the profit is in servicing and spares - but the margin on a 7 series BMW might be more than 50%. In effect, as you go up the scale the incremental purchase price of every improvement gets higher. But humans are hardwired to a degree to accept this, which is why, for instance, a footballer only slightly better than another one may be paid ten times as much. It has its origins in natural selection where a very small competitive advantage is enough, perhaps, to ensure that h neanderthalensis is entirely replaced by h sapiens, or very slightly bigger antlers may cause one male deer to get all the nookie and leave the others out in the cold.
It takes a lot of cold, hard acceptance of financial reality to decide that if phone A is 90% as good as phone B but costs half as much, the opportunity cost advantage is with phone A.
I'm not sure if that's a good answer to the question, but it's an answer.