You know, being on both sides of the "tax" fence (being an individual tax payer AND a business owner), I feel that we should be transparent and should not allow tax evasion. That being said, I also believe that we should fix our tax system, because all the business like my own, are getting ripped new holes that just shouldn't exist. Which only furthers my resolve that tax evasion shouldn't be allowed, as that doesn't make it any easier for positive businesses. Still though, a lot of our B&O taxes are not going to the people, to our infrastructure, to the kids or to anything truthfully beneficial to us, our country or our world - most of it, is going to WARS, government non-sense and political pay checks.
So yes, tax evasion should be completely banned - though it cannot be done without also fixing the taxation system.