A decent-sized house in America is 2000-3000 sqft (185-275 sq meters). You will usually get two floors and a two car garage. And if you pay a little extra, a finished basement as well.
And of course, the entire house, top to bottom, back to front, has central air-conditioning and heating, controlled from a single point. If you get fiber-glass insulation in the attic, properly insulated walls, and double-paned windows, you can easily survive a Midwestern summer (during which the number of days the temperature is above 40C can easily be a dozen or more) without ever opening a window or breaking a sweat, and you won't break the bank doing it.
Not being able to do that in Europe is probably the biggest reason why I would never able to live there (or in places like Seattle, where central air isn't common). Even if it only gets hot occasionally, having to essentially "condemn" most of the house to the outside temperature and just sit inside one room the whole day is not a lifestyle I could tolerate.