Nah, Over here in the UK I think we are a bit more reserved, certain parts of the county may have a higher ignoramus level but for the best part I don't think we are too bad. I have never been berated for sedate driving. I live in the country and here the country is narrow windy lanes so I think drivers have grown to expect slow drivers. Stick um on a bike though and it's a whole different kettle of fish.
I think even in the countryside in the UK you'd get people leaning on the horn if you were driving your car at 15mph.