I find it a bit strange that anyone would be willing to let a stranger sent by an app, someone they have never seen before and are likely to never see again, go through the privacy of their home. As a parent of a small kid ever in a need to keep the house in order we hired a cleaning lady based on references we double checked. And even then when the lady arrived at our house we first set with her and had a nice talk over coffee so we could get an impression on what kind of person is she.
I have no doubt that there is a market for a faceless service, but I have doubts this is one of them. I am sure it is the human contact and trust you developed with customers is what made them call you once you went your own way and not call the app again.