I think you've got to look at this as a process of gradual refinement in which both government and industry participate. The government wants to achieve its ove

I think you've got to look at this as a process of gradual refinement in which both government and industry participate. The government wants to achieve its overall objectives of reducing emissions over a long period of time (decades); it knows that if it just set the emissions targets at the target on day zero the entire industry would fail to meet them and the industry would collapse. So the regulations have to be set with some idea of what is currently achievable or within reach of the industry given an economically feasible amount of investment. So the aim of the regulation is to push the industry in the direction you want them to go at a rate which gets everyone to the destination without destroying the industry. And every so often the regulations need to be tightened to keep the development process moving forward.