Our friend moved back to Finland and was told she could not take her 2011 Prius there because the tank bladder would melt from the gas. Anyone heard of this? Is this another negative story put out by the competitors?
Yeah, I think there is some confusion here. It is very unlikely that the fuel in Finland would be so different as to be capable of melting the bladder. It is possible, however, that they have rules/regulations that prohibit fuel bladders inside the tanks, but as was already pointed out, the 2011 model year prius does not have such a bladder. 2004-2009 prius (gen2) did have a bladder in the US, but not in most (all?) of europe. So for those model years, a US import would be different in that respect from those purchased locally. That being said, there can be other concerns when transferring cars from one country to another; subtle things even, such as requiring always-on headlights which are not standard in the US models.
While there are many emisions/safety/performance regulations that might keep a U.S Spec Prius out of anouther country, the melting the bladder is not one of them. (This does not mean it will meet regulations, just that it won't melt)
New cars have to meet Europe wide regulations and if registered in one, is legal in others. However, each country has its own regulations for imports. A US Prius is perfectly legal here in the UK once you have orange turn signals at the rear, white side marker lights at the front and a rear fog light. As far as I know, petrol has to meet certain common regulations across Europe too.
To my knowledge there is no way to "melt" a bladder tank with fuel. But I sure don't know what happens in a accident/fire scenario...maybe some countries have rules for that. Further stressing, no bladders anyways in Gen3 (2010+)