I don't think it is just the French. I have Polish friends that aren't into it either. I think most of Europe isn't really into peanut butter.
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.
Fwiw it's available in every supermarket in Germany and for me it's a pantry staple.
https://www.ers.usda.gov/data-products/chart-gallery/gallery...
https://www.globaltrademag.com/the-european-peanut-butter-ma...