I'm not getting a route from your waze route link. However, if I route from Fountain View Dr, Midlothian, VA to Presidents St, Reston, VA the second route is currently the route that you propose. Waze thinks that at the moment its ten minutes faster to go to beltway (that route may require you to pay for the express lanes). Seems like waze is doing a good job here to me.
http://www.waze.com/livemap/?zoom=8&lat ... &to_seg=-1