Ulysses was first published in Paris during the 20 years that Joyce lived there.

>I thought only the US ranks it high

Joyce never even set foot in the United States... You could say this about The Great Gatsby, which US sources might rank in the top 5 compared to 46 in this list.

Right, Great Gatsby is another book one could highlight, where it's surprising that it is on the (french) list, while it would be on an US list. But I haven't read it, I do not know whether it is a good example for the difference between a good or important book and a memorable one.