It's not preferred. All the leading economic models and experts are in agreement that a flat carbon tax is the way to go (on paper). The problem is political f

It's not preferred. All the leading economic models and experts are in agreement that a flat carbon tax is the way to go (on paper). The problem is political feasibility and public acceptance. It is a lot easier to pass carbon trading schemes, emissions targets and caps, and renewable energy subsidies-- even though all of these end up costing consumers more than a simple tax would. I recommend looking into the work of William Nordhaus for more on this topic.