The Paris Agreement was never an agreement to implement a carbon tax on the countries involved. It is an agreement for countries to reduce their emissions and carbon footprint. Some countries decided to implement a carbon tax and put that money towards investing in cleaner, renewable energy sources. I don't see how that is not a worthwhile result. Also a carbon tax is an incentive for the consumer to make more energy conscience decisions and the free market follows the consumer's decisions, hence resulting in better technology and less emissions.