Here is an exercise you can try next time you are in a US city on a weekend. Take the Sunday real estate ads, and visit as many houses as you can conveniently fit into the afternoon--1 to 4 pm is the usual open time. See what you see in the way of books. I don't think that you will find that things are radically different here. I've seen houses with very interesting bookshelves; I've seen plenty with pretty scan holdings.