Yet some manufacturers get it right.
I had to recover/repair a Philips '4gb' MP4 player, I formatted it via a PC and found the memory to be 4.3gb , when repaired and the firmware re-installed it reported an expect 4,000,000,000+ bytes according to windows file manager.
So the manufacturer had included an additional 300mb you'd never normally see or hear about to contain the operating system.