It may be the case that there is so little regulation in this area as in many other working practises and I think we need some as every Tom , Dick and Harry will think they have the ability to construct these sometimes complicated structures that do need some professional attention.
I have heard of some terrible accidents in America where decking is still colossal in the home improvement market and will be for years to come.
Local Authority’s should see what is going on in there back yards at least and offer there consumers a little protection.