I doubt cellular stack certification is what's driving prices up. I used to make mobile phones back in the late 90's, and even then we constructed mobile phones

I doubt cellular stack certification is what's driving prices up. I used to make mobile phones back in the late 90's, and even then we constructed mobile phones as an n-way system. The cellular stack runs on a subsystem on it's own, and all communication to that system is done through the good old fashioned Hayes Command set (https://en.wikipedia.org/wiki/Hayes_command_set https://en.wikipedia.org/wiki/Hayes_command_set). This subsystem is responsible for everything cellular, and it is certified by itself, meaning when you make a new phone model, you put in the same certified chip as you did in the last n models, and it's automatically certified (wrt to the stack anyway). There are still FCC/CE certifications to be passed for all electronic devices, as well as devices containing radio emitters, but those are cheap in comparison. Apple has always priced their products on a level of what they think people are willing to pay. It is a luxury product, and they (used to) spend a lot of time making sure it feels like it. From the very moment you enter the store, to you open the box, to the onboarding experience. Most Chinese manufacturers have more of less copied the experience since then.