I have always put it down to "Do As I Say, Not As I Do" syndrome.
It's probably not so bad as long as they change footwear.

Mind you, in some places I have been (overseas), the biomeds have been the most prolific "offenders" (
mea culpa).
But the nice thing about wearing theatre clothes all day (week) is that you can simply bung them into the hospital laundry and draw out a fresh set. You know it makes sense.
An added plus:- no ties in the theatres.