Yes in the main to go to court either some one must die, or some one must lose money, so if an electrician claims to be a scheme member and is not, then the scheme provider is losing money, so they will take him to court. If some one dies it does not really need the Part P laws to prosecute, so again unlikely to clarify what has been written.
We have seen with the TV licence law how it has changed over the years with court cases, the wording was really bad to start with, it said you needed a licence to have or use an apparatus to receive TV transmissions, which when I went to school was called an aerial. That was clearly not what they mean, painting the aerial black and white did not mean you could use a black and white licence. There have been parliamentary changes, you now need a licence to use iplayer, but in the main it was court cases which modified the case law.
With Part P there is a major problem as there are few definitions given, and where they are it is open to abuse. So for example I want a new kitchen (remember I live in Wales) so I rip the old kitchen out, so there are no food preparation surfaces, so it's no longer a kitchen, so I can modify the electrics as much as I want, then new kitchen is installed, but you don't need to register existing work, so no fees. We all know that is not what is meant by the regulations, and that I should pay the LABC to register the work, but considering across the boarder kitchens are no longer special places it unlikely any Welsh council will bring a court action when some one does such a trick.
I know in a village near me half is English and half is Welsh and a few electricians have done work thinking the house was in England, and only after being asked for the compliance certificate did they find out it was in Wales.