Soft wash?

Just wondering, why is it that companies that are doing soft wash cleanings for roofs are coming in at such low pricing. It seems as if they’re coming in around 6 to $0.08 a square foot. How long would you experts say it would take a 3500 square-foot roof two-story to complete doing soft wash. When offering soft wash roof cleaning are you rinsing walls windows and doors under that one price? Or are you only cleaning the roof.? Thank you for your time

Where are you located?