Funny; I have a Polish friend who lives in France and LOVES peanut butter. When she travels to the US she always maxes out her luggage weight with peanut butter on the return trip. I'm sure there are outliers everywhere.
An Italian friend said his mom would say "who puts peanuts on bread?", but she'd slather hazelnuts and chocolate (Nutella) on bread all day long. I think it's just what people get used to.