I take it back.
The daily changing wallpaper suffers from the same problem as its desktop equivalent - Americans.
Americans, and particularly MS, aren't aware of other countries or timezones. The concept has never been considered by them. Thus, as with Bing Desktop, the background doesn't change daily, but at some strangely offset hour of the day.
I'd like to see a different wallpaper when I get up in the morning, that's cutesy. But having it change whilst on the way to work is just a momentary puzzlement.
It's the same throughout MS, they're not prepared to market anything outside the US.