Why do you think the definition of voluntary work will help to avoid paying taxes?
Many countries are actually ruled by the crown. In The Netherlands for example it is the crown (represented by the King) that signs every law. Every law starts with the words “We, Willem Alexander, by the grace of God..”
This means that the law was signed under the assumption that the law is valid because the King has the grace of God. Since this grace of God has never been prooved, it is a possible stand to question the validity of the law.