The CAA will only go for a court case if they think they are going to win, and have very good evidence to prove it. There's a lot of people out there who get off on a technicality and receive either a formal caution or written letter.
As always, the people who should be prosecuted are the ones who always get away with it.
I thought the bike rider at Kemble had big cajones to appeal......and then got a bigger fine!