I see now.
I think that Co's who bid their PM's on a low margin hope to "make it up" with quoted and approved repairs as a result of those PM visits. This brings up my previous observation about NAS, that being: once you have installed new units on a client's roof, there is nothing else to do during those PM visits. That forces you to always be in site acquisition mode, leaving a scorched earth of wary clients and new equipment in your wake, and making increasingly unrealistic promises to the new clients. This approach "gets around" in the industry, and eventually, with many other choices for the same services with a better business model (First, Comfort, USM, CLS, Smart, etc) the NAS model will soon implode.