Probably because AC is newer. Home heating has been seen as a necessity for generations, so most people have had it, while there are still plenty of people who

Probably because AC is newer. Home heating has been seen as a necessity for generations, so most people have had it, while there are still plenty of people who lived without AC for large chunks of their life. Plus there's the San Francisco factor. AC is simply not necessary there most of the time for most people. Even when it is hot, it is usually hot/dry, and tends to cool down at night. Thus there are many people here who think AC is a needless luxury everywhere because they personally do not need it.