I've seen the system start from scratch and develop up to the current rules. I've seen the Crown allow certain protected witnesses to lie about the benefits they have received. I believe that, under the Italian system that you describe, they are not compelled to disclose the benefits they have received. From what I understand, we can grant those benefits following the testimony, whereas, under the Canadian and American systems, we have to give witnesses all benefits before they appear.
On May 31st, 2007. See this statement in context.