Your assumptions are wrong, this is a strictly theoretical discussion for me. I don't use GPS apps to tell me exact travel times or traffic info.
Okay, so then theoretically what you would like to happen can not. It will take to much CPU power and data to work on a global scale. Also accuracy of the program working would hinge on the "flags" you mentions which would not be very accurate due to inconsistency in data. If you ever look at or watch your local city traffic website you will understand about the inconsistency I am talking about. Now of course some cities/locations will have better traffic data/info than others but then using that data for a predictive travel time program would create a good experience for some and bad user experience for others.