Totally agree, the "live" subtitling on BBC is remarkably bad.
It's way worse than even using a cheap computer with open source solutions - it's strange no one at the BBC decides to resolve this as it would be easy and could easily give the public a far better result. Even if you took a hit on the most obscure words, off the shelf would outperform the current process by a country mile.
Interesting side note: if ever subtitles are turned off, or we are watching TV elsewhere, me and my wife can't 'hear' well. Even if the volume is up. Like we've untrained our ability...