In francophone Switzerland, they use septante, huitante, and nonante for 70, 80, and 90, respectively. Much more sensical, imo.

Oh and bonus point for the fact that filing personal income taxes absolutely sucks and is an undue burden on the working class. With carbon (or other Pigouvian) taxes, only businesses would have to account for their carbon. With land value taxes, the government can easily calculate the value of land by similar statistical methods it uses for assessing property values for property taxes and then just tell you what you owe. With severance taxes, only businesses such as oil and mining and timber companies would have to do the accounting.