[soco]

I don't know about "most gps software" but I have a Garmin doing that and Google Maps does the same. So in my experience it's 100%. Now if such well established software products didn't figure out such basic stuff, either we're calling it wrongly "basic" (and it's a difficult problem) or the responsible factors just don't bother. The major difference is though, while gps navigation can do with frequent recalculations, realtime obstacle avoidance less so.