When we had the English review of Part P some good points were made, those in favour of scrapping it pointed out percentage of population who suffer with alzheimer's or similar before retirement age, and point out the number of electricians who have been thrown out of a scheme is a lower percentage, and there was nothing stopping them joining another scheme provider, information is not passed provider to provider, also to require people to be a scheme member is no different than requiring them to be a member of a union and closed shops have been banned.
If you lose your driving licence the courts require things to change before you get it back, but loosing scheme membership there is no such controls.
I do feel there is a huge difference when some one charges for there work, to some one who does it either DIY or a favour, however it's too easy then to get around the law, claiming faulty work was done as a favour.
We can all make mistakes, but some one doing work without the testing equipment that's not a mistake.