correct alignment on camber and especially toe and runs straight on a non crowned road but the steering is still not centered all that is needed is a fine tune on the tie rod ends. For example if the wheel is in a left turn position and the car runs straight as noted above then tie rod on both tires needs to be toed to the left (driver side) in an equal amount.
I do front and rear toe adjustment on my car with a story stick and then fine tune the toe and steering wheel center as described above, runs true as a dart and no drift and even tire wear.