Actually, don't they have a separate set of bulbs for DRL. The angel eyes are when the side markers are on (first click on any headlight switch)
US Cars with no DRL have no light sensor on the dash. If you look, there is a blank spot for one. The only sensor there is the Climate System sensor.
It would seem that cars w/ HID which are also equipped w/ fog lights could easily use the fog lamps as DRL's unless they're considered too low.
Doesn't the Chevy Avalanche use this technique? The DRL are mounted into the foglight housing at the bottom of the airdam, below the front bumper.