What kind of self-regulating system of taxation are you talking about? Lol. Politicians couldn't keep their hands out of the budget. What they do and politics? Maybe you believe that they go into politics to make the country better? They will never give control over taxes and nothing to even speak on this subject.
For that reason I am sure most of them will do anything in their power to maintain the current system the world uses after all, it is the most convenient system for them to be corrupt. If there would be a self regulating system of taxation, they wouldn't be able to do what they usually do. It will be hard to convince them to switch with this self regulating system because like you said they aren't in it to make the country better but to give themselves power and money.