I did read the whole article, but I interpret cash as meaning paper currency. Especially when they say "Not just coins, but cash" it leads me to believe they ar

I did read the whole article, but I interpret cash as meaning paper currency. Especially when they say "Not just coins, but cash" it leads me to believe they are talking specifically about banknotes. I re-read the article and they do clarify that they are talking about Europe specifically, both in the book title and the interview. Perhaps 3AM isn't the best time to post.