Taxation is the price we pay for failing to build a civilized society. The higher the tax level the greater the failure. A centrally planned totalitarian state represents a complete defeat for the civilized world while a totally voluntary society represents its ultimate success.
In Britain the centrally prescribed welfare to work system short-changes the young unemployed. Transport housing and education are over centralised.
If you think aficionados of a living Constitution want to bring you flexibility think again. You think the death penalty is a good idea? Persuade your fellow citizens to adopt it. You want a right to abortion? Persuade your fellow citizens and enact it. That's flexibility.