I hate to say this, but it seems common to compare price based on the hardware alone. Good software and good design cost money too. A lot of money. You pay for the development, testing, and design of all the prototypes discarded before the one you get.
Android phone vendors save a lot on the development of the system because Google and many others paid for it. And frankly, based on the make of the majority of Android phones, I don't think they spend as much as Apple on the design part either. That might explain the 20~30% "premium". You get what you paid for.
I don't understand why you're putting scare-quotes around '"premium"'. Apple do a lot of things very well, have a great brand, and unlike most of their competitors haven't been totally commoditized. That allows them to sell the iPhone and Macs at a high premium compared to the competitors. As a result they are ridiculously profitable while most other phone and PC manufacturers range from making a loss to making a modest profit.
(And actually Apple spends stunningly little on R&D compared to it's peers. There was a rather nice graph about this that I can't find, but e.g. Microsoft and Nokia spend an order of magnitude more on R&D than Apple does, while seemingly getting just a fraction of the results.)
I put the quotes around premium 'cause I don't really feel Apple charges unfairly for its products. The software and design is worth every penny of that extra 20%~30%.
My take on the R&D thing: Yes Apple is likely to be the largest tech company to spend least on R&D, but they have a much smaller range of products and market share to recover that cost. Also I was talking about the smart phone for that.
Nokia and Microsoft don't make Android phones. They cannot take the free ride on Google.
Android phone vendors save a lot on the development of the system because Google and many others paid for it. And frankly, based on the make of the majority of Android phones, I don't think they spend as much as Apple on the design part either. That might explain the 20~30% "premium". You get what you paid for.