https://www.euronews.com/2018/05/16/polymer-vs-paper-banknotes-which-one-is-better-for-environment-

If it's a question of paper versus plastic, it makes sense to print plastic notes because they are more durable. Biodegradability is not necessarily a desirable property while cash remains a traditional means of storing value.

You are right, people should want biodegradable money, but that won't happen until we overturn the distribution of money from the current Federal Reserve.

Hemp solves this, which is a primary reason it has been illegal across the world for almost a century.