The article feels a little shallow on the analysis side.
For instance I would expect this oddity to be caused by the fact that they aren't a traditional hardware manufacturer (they don't have any fabs and outsource their production) nor are they a traditional software manufacturer (their software focus pales in comparison to Google or Microsoft).
Since developing silicon and software are two of the biggest drivers in the industry and Apple doesn't focus on either, it makes sense they have a low R&D budget.
For instance I would expect this oddity to be caused by the fact that they aren't a traditional hardware manufacturer (they don't have any fabs and outsource their production) nor are they a traditional software manufacturer (their software focus pales in comparison to Google or Microsoft).
Since developing silicon and software are two of the biggest drivers in the industry and Apple doesn't focus on either, it makes sense they have a low R&D budget.