It's an international financial centre, not a tax haven. That's point number one.
Point number two, the example you described is not my understanding of what happens. Barbados provides many resources to Canadian companies that go through Barbados. It's not a hollow shell, as you described. Barbados has a legal structure. Barbados has a network of bilateral investment treaties. Barbados has tax treaties, for example, with Venezuela and China. Barbados allows Canadian companies to access many markets globally that they would not be able to get access to had they gone through what you refer to as a tax haven.