There is just no way to 'refinance' credit cards in a controlled manner, to ensure the cancelled credit card account remains cancelled, It will never be practical to work it. Unless the govt legislates that it has to be done it wont be. Its just that simple, and its very unlikely the govt would even try.
The lenders will continue to take the customers word (or written undertaking) that they will cancel their old cards. The problem with credit cards, is the customer can phone up, cancel it, and get a letter confirming. Then 2 weeks later, ring back and say they have changed their mind, and get it reinstated. (in fact the bank does not actually cancells it for that reason, to allow time for retention). Everyone knows this.
*A possible solution would be to require that all credit card cancellation requests in writing are irrevocable, and that the new provider must take this form and pass it back to the previous provider.
*Actually, could something like this even already be in place? I cancelled my westpac card recently,only had it 6 months. The guy didnt even ask me why I wanted to cancel it, he just did it. was all over in a couple of minutes. I was so disappointed they didnt ask, let alone offer me bait to stay.