I would suggest that people separate "regional" auditions (which are usually taped on site) and "home" made tapes when telling of their experience, since they are really not the same thing.
Also, I do think the instrument (as well as the school) matters a great deal. My D's experience last year was that neither she nor any of her flute friends had a single acceptance from their (home)taped auditions to ANY school; and none of them were accepted into any of the top conservatories unless they auditioned live. This included a student who is now at Juilliard, one at CMU, one at Peabody and my D who is at Rice. I think these were talented players, but when the "live" pool numbers in the hundreds, the schools can choose to only really consider those live auditions.
She had 2 other friends (oboe & clarinet) who were accepted using home tapes, but to University Music Schools, not to the conservatories that they sent tapes to. The oboe student was accepted from a live audition to NEC & Eastman....so I feel confident that he was qualified for other conservatories, he just couldn't afford all the travel.