This is another indication that something is shifting the faster you go. It is more noticeable because your covering more ground. It pretty obvious to me that a toe angle is changing as your moving. In some cars, this is normal but not drastic enough to cause problems, and manufacturers compensate by specs being toed in ( wheels slightly pointed inward) because as a vehicle moves forward most suspensions (at least ones with positive caster, which is almost every vehicle) try to force the wheels outward.
The obvious reason it's not showing up on the rack is because the vehicle is not moving. The tech needs to do his due diligence and check each component that would cause this problem. Things that need to be looked at have been mentioned but I'll mention them again. LCA bushings, Inner and outer tie rods, steering rack bushings, and the rear lateral control arm bushings.
One other thing, just because the specs are in the "green" doesn't mean it's right. This drives me absolutely crazy. For example the spec for our truck's caster angle is 1.7 to 3.3 degrees. Now if the left side is 1.7 and the right is 3.3 it will show as green but the cross caster is 1.6 degrees and the vehicles will pull to the side with the least amount of positive caster, which in this case would be to the left. I always trained guys to get the spec within .5 degrees or better on the cross caster and camber to eliminate pulling caused by those angles. Also, to compensate for road crown, you want to set your caster a little higher on the right side. Ideally, for our trucks, the front caster should be 2.8 degrees on the left side and 3.3 degrees on the right side.
Can you upload your alignment printout? That would help a lot. Good luck!
EDIT: I just saw your specs on a previous page. They look ok except for the cross caster (.7 degrees) and really should be pulling slightly to the left, which would make you want to turn the wheel to the right, on a flat surface, to compensate, which is what you said the problem is correct?
