Most users (especially county assessors) of high res imaging use aircraft since it's cheaper. There are other benefits, like smaller path width and reduced angular distortion. And flying when you know there isn't cloud cover, if timing isn't critical.
So using a balloon is novel, but using aircraft in general is much more common than satellite. It just isn't all marketed to the public. "Satellite imagery" has had more success as a publicly known term than "aerial imagery", and it doesn't occur to most people that they're different things.
>Whoa. I didn’t know that daily satellite imagery was available to civilians.
There at least used to be a requirement that imaging satellite operators only release imagery up to a certain resolution, and that anything higher was subject to review/ approval (presumably from NGA). And in exchange for this cooperation, the operator gets a nice federal contract for providing NGA copies of everything imaged, plus they get their launch permit approved.
>How much of the planet’s surface is imaged and available daily?
I think Planet Labs claims full coverage every three days? But that doesn't equate to 1/3 every day, and coverage that isn't evenly distributed, due to the nature of orbital ground paths.