Now accoring to this article: https://www.telegraph.co.uk/news/2016/07/30/britain-banishes-plastic-bags-as-5p-tax-sees-usage-plummet-by-6/?fbclid=IwAR3avBXNeV1n3Emb8weHygZnCJdKo6xLIPWJB0J0gyHhXXh6FQf8MJKrznc
just by putting a 5p tax on plastic bags. The total number used plastic bags has fallen from approx 9 billion down to 1 billion.
Now based on that i wanted to see why this tax led to a distortion of the price mechanism, creating socially inefficient tax rates that also resulted in deadweight losses as seen in the uploaded figure. Is this correct done/understood?