Thousands of them. We gots ta keep it short if we want 2000 airplanes. ADS-B does everything for everybody, so long as there aren't many planes, and you have billions of dollars to build and operate it. It might fail. We sell these books full of neat color maps.
Paper is expensive.
I wonder if anyone would buy it if we put the whole U.S. on one CD Rom, same colors, name everything, include everything, because computers can zoom down to the foot level. I wonder if anyone would buy it if we put a GPS input on it. See where you are. Record a travel log. Have it tell you directions.