sorry, I came from old school or a small one where it wasn't always about the money and shower facilities in the dojo? really? Never had one...
Also, most gyms offer tons of additional classes that aren't extra. For example, in my gym you can take jujitsu, pilates, Spin, Zumba, Yoga, water aerobics, and those were to just name a few. They have tons more. And each of those classes has an instructor. At my gym, i pay 90 bucks a months and that includes my family, which is six strong. If I had to pay extra for my family and those classes I would go broke. Thank gawd my gym has some sense and not crazy like some dojos that charge to breather air in their classes.
Private lessons, are using up more of the instructors time, not necessarily groups classes. The class would be going on with or without you so why charge extra if someone decides to goto each group class offered?
90 percent of good abs is your nutrition