There are rumours that a license scheme will be introduced within 5 years, I suspect that "shoud" clear up the discrepancies.
At the moment, the only real thing in question would be competency. Having the card goes some way to proving that but is not necessarily a cast iron guarantee.
I have worked with many guys over the years without the card and many with. Some without make those with look like rank amateurs and vice versa; to claim that someone can't be an electrician without the card is probably unfair in my opinion. The best guy I ever worked with, fast, neat, knowledgeable with a natural eye and flair for the business has never had a card and couldn't care for the JIB. He has also earned more money than most. Another guy I worked with was ex-Navy and could do complex control systems whilst supping tea and doing the Guardian crossword. He was a subby and didn't have a card either. Whilst an apprentice, I worked on site with a guy who managed the stores (because of his incompetence) who was a card holder and one of the lads I done my apprenticeship with now works for a wholesaler as a delivery driver.