Apple is being sued in the US for "false advertising" regarding the usable capacity of its 16GB iOS devices. It's a familiar story with a familiar underlying moral.
SiliconBeat reports on the class action lawsuit, which claims that Apple is essentially deceptive in selling devices where a significant proportion of the available storage space is taken up with the underlying iOS 8 operating system. On lower end devices, that can be nearly a quarter of the available space, and, as per the lawsuit, Apple leverages this by selling iCloud storage to bolster available storage.
I'm no expert on California law, although it does seem like a terribly prototypical "silly" US lawsuit to my eyes. That being said, Apple's arguably a little worse than most in detailing how much real space you'll be able to access on an iOS device.
As an example, the comparison page for iPhones has small print relating to the available storage, but it simply relates to the way Apple counts gigabytes, stating "1GB = 1 billion bytes; actual formatted capacity less".
That's not terribly useful, and neither is the fact that Apple still refuses to put microSD card readers on its iOS devices, which would also solve much of this problem. You can at least get a variety of iOS-compatible wireless drives to boost your available device storage.
In any case, tech companies being taken to the courts over available storage is an old story — here's a suit relating to the original Microsoft Surface that takes up much of the same rhetoric from 2012 — and the lesson remains the same. Don't expect the operating system on a device to take up absolutely zero space, and, where possible, expand storage if you're stuck on a lower-capacity device.