The issue I have with the Sunwings operation is that it appears that Sunwings operates the ECA aircraft in Canada in the winter with Canadian pilots and then operates ECA aircraft in Europe in the summer, again with Canadian pilots.
If an equal number of ECA pilots went to Canada in the winter as there were Canadian pilots in Europe in the summer then that would balance things out.
NB. This is not an attack on Canadian pilots - I do not believe that Canadian pilots have any say on whether they are given EU work permits or not.