The definition of a tax haven can vary widely and depends on many things. You have given one from an economist. To some Canadians, Alberta is a tax haven. To some people, it is always the place where you pay the least tax. To others, as you say, it will be a place where there is a structure that favours avoidance. It all depends on the situations and the structures. However, in the usual definition, a tax haven is essentially a place where there are protections that allow aggressive tax avoidance. Tax evasion is the more usual term. When we are talking about tax evasion, as Mr. Purre said, that is an entirely acceptable definition. However, other people might go further and even include Alberta as being a tax haven within Canada. So the concept is an open one.
On March 21st, 2013. See this statement in context.