There's a ton of space in the US between the coasts[1], so people have become accustomed to large houses that they can make "their own", so to speak. It's just a different culture.

[1] A lot of it is still unused! My hometown in Texas has actually "grown" in the past ten years towards unused land to build new neighborhoods and schools. I can't imagine that there's large amounts of land in Europe to build entire new communities, right?