To be fair, many people don't really know how to multitask on Windows or Mac OS (alt-tab, cmd-tab, etc.) either. It's not like the buttons have icons or anything on-screen to emphasize the key combo can be used to multitask.
Not trying to defend Apple, but really just that interfaces in general haven't always been perfect and still have issues, not just one (mobile) platform.
Not trying to defend Apple, but really just that interfaces in general haven't always been perfect and still have issues, not just one (mobile) platform.