I see your point. Teachers, like other professionals want to do a good job, for them that is evaluated on how well their students progress. So anything that leads to student improving, makes them a desireable student. Practising, being attentive, enthusiasm etc..

That explains why our teachers always seem to like us, even though we our not a major source of revenue for the studio. We practise, we go out dancing once a week and dance a lot when we go out. We always are mentally into the lesson. We also try hard, sometimes to much . I also really try to understand the dance and not just learn the mechanics.