If it was part of regular classes then they could just practise it at home.
I meant it is part of regular classes in some of the cities I mentioned. These classes vary. Some are half an hour shines and body movements, and rest half partnerwork. Some are 45 minutes on shines/body movement and 15/30 mins of partnerwork. Some are an hour of shines/body movement and 30 minutes partner work.
I rarely seen regular shines class that doesn't include teaching body movement. I am not talking about Congress classes, which are largely useless because they are one time only.
Now that I am trying to recollect, when I was a beginner, almost every instructor started classes with at least first 15 minutes doing footwork/shines. Then partner work for remaining 45 minutes. No one ever consider the free classes at a club before dancing started as a serious class where someone could learn. For instructor teaching free classes at clubs was a way to new students join their regular classes which were offered in the studios. At that time salsa was the only game in the town. There was no bachata or Kizomba to compete.
Watching how well people could dance also made beginners seek out better classes to get good. The more people there were who were regular and good dancers, the more beginners would gravitate towards making serious efforts to take classes and get better. I observe a kind of direct correlation between number of good dancers and beginners that enter the scene. A scene with good dancers also has more beginners interested in salsa.
Out here when I dance salsa with bachata girls, they aren't that bad. But definitely apologetic about not been good at salsa. However in the local scene I have yet to come by a good bachata follower who isn't good at salsa. I don't think it will last long. BS will eventually creep up in here too.