To my knowledge, most at least similarly situated countries, like the United States, and even England or the United Kingdom, with its permanent tax simplification office have yet to achieve any major victories in this area. From a political perspective, it's obviously very difficult to get rid of perks, whether they're introduced by the current government or by former governments.
South of the border, one good example is the mortgage interest deduction available to taxpayers. You have to be an itemized tax return filer to be eligible, but virtually every economist or tax law professor who has looked at this deduction would say that it makes no sense, yet it persists over time. Many Canadian taxpayers, I suspect, would want a similar benefit.
I'm hoping that the U.K. efforts, which are fairly novel and fairly recent, will bear fruit in the future, but the key, I think, is to appoint an independent panel to investigate this over a period of years, versus the advisory panel's work, which was completed all in one year. I had to file my report on tax simplification within six months, I think, after I received my instructions, and it was simply insufficient time to really take a close look.
The only way to get any traction, in my opinion, would be to appoint this independent body. That way it insulates the government from a political critique if it's perceived that this body is to be unbiased or non-partisan. But yes, I don't think most countries have had any luck toward any significant or material tax simplification, to my knowledge.