In the good old days of the C150 we all worked in MPH and the standard speed to climb and for final approach was 70. I think this and the rough equivalent of 65 kts in the C152 is used because it makes life in the early days of teaching the landing phase. If a student maked a B**ls up of it when approaching at 1.3Vs you could be bouncing back 10 feet into the air with "nothing on the clock" and an expensive unrecoverable stall to follow. Approach at 70 (65) and the immediate application of power puts you nicely back in the climb and in a few seconds "bloggs" has recovered his composure to take back control and have another go. Such speeds don't matter on a 1000 metre runway, but what may have happened is that when the skill level of the student is sufficiently advanced, insufficient emphasis and traning is given on approaching at 1.3Vs to achieve the "performance" or "short" landing as we used to call it.