Can't say I've ever been annoyed by American tourists, but then again I don't work the tourism business.
And again, you use these words like norms and values as if you assume that there is some objective "American" way of life, set in stone for all ages and situations, to be never changed or questioned. And that is just a fantasy, that is not how cultures work. Civilisations and societies are in a constant state of flux, they don't exist in a vacuum, they influence each other and some elements are discarded if they outlive their usefulness.
Some posters earlier cited the Austro-Hungarian Empire as an example of failed multi-culturalism. In my view that is complete bollocks. That empire didn't fail because of its many cultures (at least not primarily), but because of a lack of change and adaptation. The Austrian ruling classes had one vision of their Austria, that of a monarchy dominated by German-Austrians, ruling over a multitude of people. When nationalism developed, that vision was no longer viable and so it was replaced by a different Austria. Of course it took two World Wars and some rolling heads to get there, which leaves you wondering if the same could not have been achieved with a bit more self awareness.