I rode my first motorized two-wheeled vehicles (50cc and 150cc scooters) in a place (Taipei, Taiwan) where this sort of thing was standard operating procedure. My road awareness skills quickly became honed.When I had u-turn lady come out in front of me, the other driver had absolutely no regard for checking for oncoming traffic and if I was a car and wasn't alert then her passenger would probably be dead.
Although, it is much different here. These sorts of things occur less often. And that's why it can be more dangerous. It's usually some random numb-skull who pulls out in front of you. You can easily become use to this sort of thing not happening, and this could lead to you letting your guard down a bit. You can still be 100% aware of the road and other drivers, but you could easily be lulled into not anticipating stupid driving behaviour from that random idiot.
Ability to anticipate a driver's intensions and actions is equally as important as road awareness and mental alertness (unless this is already included in your own definition of these terms).