I disagree. Several times in the book Harry receives indications that while the Death Eaters are consolidating their power in Britain, Voldemort is busy running around the Continent trying to track down the Elder Wand. The European magical communities probably mis-intepreted Voldemort's actions, and thought he was getting ready to make a move against *them*. They were probably too busy seeing to their own defenses to worry about what was happening in Britain.
So basically, the entire magical world left their comrades in Britain to suffer under a Communist style dictatorship.
I think it was a plot hole, rendering the whole premise of the Tri-Wizard Tournament in Goblet of Fire pointless.
But I still liked the book.