Because flight schools don't just put out ads that say "Hey, we offer scenic aerial tours of the city". That's not what their business is for, and that's not what they do. And no tourist shows up to the city and says "hey, lets contact the local flight school and schedule an introductory lesson so we can see the city from the air". My business would literally put out brochures and flyers around town, in hotels, restaurants, etc. advertising our scenic aerial tours. We would take large parties, and would allow them to have some say as to where they want to fly and what they want to see.
I agree. Which is why I get puzzled when tourists keep saying "Oh, Nashville is such a beautiful city." I've lived in middle TN all my life and I still can't see what the big deal about Nashville is. But...BUT!!..... People seem to love it, and love to party in it. It's the new "it" city. People are already partying on pedal taverns, buses, trolleys, and all sorts of other stuff. Why not offer a plane they could buzz over town in for an hour or so?