We don't need another scheme, or a new system. What we need is for those with the power (the Government) to focus on the issues across the construction industry, grow a spine, and enforce the regulations that are already in place.
There are IMHO only two 'grades' of tradesmen in any field, those that act professionally and complete work to a high standard, and those which don't. All the qualifications, length of time in the trade, memberships, and fancy trousers merely hint at the type of individual. They don't prove anything.
Equal attention should be paid to, and enforcement applied to, the end users. Any customer (private, commercial, or industrial) who either dodges a standard of work, or tries to get 'matey from the pub', should be held equally liable for the penalties with the cowboy doing it. Contracts can be very descriptive, and a standard should be used. If a builder fly tips waste from a job the householder can and does get prosecuted if it's traced. This level of attention should be paid to the work done too.