Hadn’t thought of that. Is there truly nothing the rental shop can do, or we as instructors?
And, haven’t been paying attention. How would I know that this is an issue for the student? I mean, how would I know that the inability to be on the flats of the ski is a physiological thing and not just caused by a student’s unfamiliarity or discomfort with standing on skis? Almost sounds like I’d have ask them to take their boots off and watch them walk.
If they get into a skiing stance while standing still and one or both knees turns inward of the big toe, it’s a clue.
If they can’t get into a wedge with the skis flat, and can only wedge with the skis hard on their inside edges, that would be a red flag for me.
They would also have difficulty making the “bow tie” pattern in the snow with one ski while rotating their femur, because one edge might catch.
They will tend to push the tails of the skis out rather than pivoting at the foot. If one is on their inside edge, it’s a lot easier to just push the tail out.
A more advanced student would not be able to side slip.
Often a clue is that the student is quite knock-kneed (A frame) in their ski boots, but not necessarily in street shoes. However, the A frame is not always an accurate assessment of misalignment.
I read an article once that stated that skiers with alignment issues either were terminal intermediates, or often quit the sport, if undiagnosed. Also, those blessed with good alignment are more likely than others to become expert skiers due to easier acquisition of advanced skills.