[TremendousJudge]

I'm from a place that (I'm told) has similar weather, and it's common for people from colder climates to complain about lack of insulation. The quick answer is, here you don't have winters that are as cold, therefore developers can get away with shoddy construction without killing its inhabitants... so they do. If you built something like this in Toronto, people would literally freeze to death inside, so it can't be done.

Also, take into account that spring/summer is warmer, and construction practices also have to take this into account.