You're absolutely right, there are huge swaths of airspace that rarely see traffic. Imaging satellites have an inherent advantage when it comes to total coverage but proportionally, a small % of all images captured in an orbital period are of interest at that point in time. We look at our approach as an opposite, complementary offering that optimizes for revisit in well-established and predictable routes around population centers (and whatever else lies in between takeoff and landing).
Most airports are zoned industrial and located within or on the edge of cities and towns, so we can provide more frequent updates of areas that are of greater value to customers monitoring supply chains, construction/site development, estimating traffic flows, etc. High-revisit is equally important at cruising altitude over much of the country where demand for agricultural/environmental monitoring, crop yield data, etc. is of similar interest.
All this to say coverage is a known limitation, but based on those reasons I think (hope) we'll become the yin to satellite imagery's yang.