I think it is a very good idea to make tax returns open to view. It's a "social no no" in this country because those in power encourage us to think that such transparency equals some sort of communist plot - just as Obamacare was viewed by many in the US. You would think people would have more sense, but apparently not.
Some of the very highest paid people obviously pay much more in tax than the very lowest paid because they earn vastly more money (those that don't use all sorts of legal and illegal measures to avoid paying tax, that is.) If you're receiving £2 million per annum you should be paying more tax than someone receiving £18,000 per annum. Some people are wealthy enough not to work but live on the profits derived from their investments and, again, some of them will use all sorts of loopholes to avoid paying tax. And yet the people who work to produce those profits cannot opt out of paying income tax and, because they are subject to 20% VAT on goods, pay - relative to their income - much more tax than wealthier individuals.
It is only through taxation that a country is able to provide the sort of infrastructure and stability that businesses need - roads, railways, health care and education for employees, public order, etc. etc., so business owners and investors should be prepared to pay their share.