Why is subtitling and closed captioning so bad?

Why is the (global) state of subtitling and closed captioning so bad?

a/ Subtitling and closed captioning are extremely efficient ways of learning new languages, for example for immigrants wanting to learn the language of their new country.

b/ Furthermore video is now offered on phones, tablets, laptops, desktops, televisions… but very frequently these videos cannot be played with sound on (a phone on public transport, a laptop in public places, televisions in busy places like bars or shops,…).

c/ And most importantly of all, it is crucial for the deaf and hard of hearing.

So why is it so disappointingly bad? Is it just the price (lots of manual work still, despite assistive speech-to-text technologies)? Or don’t producers care?

UberAlex responded:

It’s interesting to look at the fan-sub community, where they can be a labour of love. They are often considered far superior translations to the official ones. http://en.wikipedia.org/wiki/Fansub