Wayne,
The mills will address commercial and residential differently for a couple of reasons:
Typically, a residential customer trying to avoid paying for carpet cleaning is not going to use a rotary, so the mill doesn't have to stress not using one. The least problematic way for the homeowner to clean their carpet if they want to do it themselves would be by using an extractor and hopefully SoA chemical that comes with it. Mostly the dissatisfaction homeowners will have with their carpet is due to their not cleaning the carpet at all.
Typically, a commercial customer trying to avoid paying for carpet cleaning will buy equipment from a janitorial supply house or get their janitorial contractor to do the work. The cheapest piece of equipment is a rotary, but it takes some training to use correctly. The most brainless is a walk-behind, but relatively weak vaccuum combined with the width of the water pick-up means water recovery is terrible, leading to more of a dirt blending than removal. Make that walk-behind a CFR and you're just moving dirt around.
After a year or so a commercial customer may complain that the carpet can't be cleaned, the mill will hire one of us to prove it can be cleaned, and the facility manager will hate us for making him look foolish... and continue to use the in-house staff.
You, as a professional, can choose whatever way you want to clean a carpet, because if you screw it up you buy it.