It is bogus to an extent, and of course individual manufacturers come into it.
They're counted in the figures printed because their handsets offer the OS on their devices. If a Motorola and an HTC are sold, that's two Android "sales".
So yes, they are comparing smartphone *operating systems* but one of these *operating systems * is on multiple devices by multiple manufacturers which when sold count towards Androids total.
What are you talking about? 1+1 = 2
If a Motorola Android phone is sold an a HTC Android phone is sold that makes two Android phones sold. How is that hard to understand. This article is about smartphone operating systems market share.