If you look at the menu with "All", "Family", "Friends", "Coworkers", initially it shows "All" and the arrow is immediately to the right of the text. I expect that if you select "Coworkers" then the arrow moves.
The problem is that many people will use those copycats as the basis for their own app designs. Not everyone is willing to really understand the reasoning behind the design spec down to such minute details as an arrow placement if he can be hip and trendy with something that superficially looks like the same design.
If a design is so easily misunderstood with such (comparably) large consequences for the user, that's a flaw in the original spec IMO.
I don't believe it's easily misunderstood; I think people just don't know how or why to create a quality implementation based on an original. The spec is actually remarkable in the level of depth it goes to teach you not only about the design guidelines themselves, but also the reasoning and psychology behind it. Really, it's probably the best full on UX specification ever produced (and I'm not saying that lightly).
It just shows that it's very difficult to get this stuff right. There's still going to be a bell curve, with most implementations and copies ending up in the mediocre middle, but overall, the guidelines might bring the quality of the overall market up. That's all we can hope.
http://www.google.co.uk/design/spec/components/menus.html#me...
If you look at the menu with "All", "Family", "Friends", "Coworkers", initially it shows "All" and the arrow is immediately to the right of the text. I expect that if you select "Coworkers" then the arrow moves.