There are not too many free and reliable sources of vector data... Tiger line data (free US source) is far from complete.. and other parts of the wourld are in even worse shape...
quering google for millions of routes in hopes to cover all the streets will probably yeild even worse vector data and possible legal problems with google for DOS attacks (BTW, they will ban your IP after ~10000 routing requests)
Again, feel free to prove me wrong and write some prove of concept code which yields some good vector data
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