A non-GPT source: https://www.lendingtree.com/credit-cards/articles/na-vs-eu-i...
Quoting the relevant statement: "American merchants pay, on average, 1.76% in interchange fees – compared to a 0.96% average in most European nations."
Most of the other sources I'm seeing are quoting even lower numbers. Transactions do seem to have less overhead in Europe than North America.