Actually, the disc manufacturers are correct, it is the operating systems that are wrong. If you don't believe this is so, why aren't you complaining that your 200GB hard drive is only 186GB?
The fact of the matter is, operating systems run on base 2 numbers, but everything else in the digital electronics world runs on base 10. For example, a kilobyte, which technically is 10^3 (which = 1000) bytes is less than a kilobyte to an operating system, which believes a kilobyte is 2^10 (which = 1024 bytes). To explain further, a DVDÂ±R holds 4.7GB, or 4,700,000,000 bytes. To a computer (which runs on base 2, or 1's and 0's) this is roughly equivalent to 4.36GB (4,700,000,000 / 1024 /1024 /1024 = 4.36). Data storage and blank media production companies have gone by this standard, although not consistently, which confuses consumers.
In actuality, 4.7GB = 4.36GiB, or Gibibytes. The same calculations can be made in conjunction with kilo/kibi, mega/mebi, etc., all the way up to terabytes, petabytes, and exabytes (tebibytes, pebibytes, and exbibytes, respectively). This is all outlined in the IEEE 1541 Standard . Unfortunately, this standard isn't as widespread as it should be, causing consumer confusion.
What needs to happen is either the computer industry needs to correctly display KB, MB, and GB in their operating systems (unlikely because of the insane amount of problems that will arise), or the storage and blank media industry needs to adopt the IEEE 1541 standard (along with the computer industry) and correctly label their products (i.e. a blank DVDÂ±R would be labeled 4.36GiB, or 4.7GB/4.36GiB, or a hard drive would be 200GB/186GiB). In return, your Windows/MacOS/Linux etc. would display your free space on your 4.7GB/4.36GiB DVDÂ±R as 4.36GiB, instead of 4.36GB, which is incorrect.
I hope this information clears up any misconceptions you all have of why things are the way they are. Currently, the industries don't appear agree with each other but they need to, as the average consumer doesn't have time to research problems such as this. It should all be user-friendly, or they're not doing their job. Maybe in the future we can all live in harmony.