Why don't thumb drive makers compensate for formatting?

This really f*cking pisses me off, thumb drive and hard drive makers say something is 300 gigs, or 16 gigs for a thumb drive, then you format it and it’s 14.6 fucking gigs, they basically take 1.5 gigs from you. Why don’t they add the extra they need to make it the size they say? It can’t be that damn hard to do, the make drives up to 64 gigs, they probably end up at 50 gigs or something. This is really annoying because you have to spend twice as much for the extra 1.5 gigs, or in my case, 832 megabytes you need. Why don’t they fix this, or at least advertise that it has a 14.6 gig capacity?