You have to remember that the preprogrammed frequencies are COMMON users of those frequencies. It is possible that for example a local hospital uses the same frequency that is often used by airline companies at an airport. The frequencies labeled "business band", "letter dot", "colour dot", etc. are often used with low power transmitters by businesses and construction companies (i.e. Home Depot). The only time you'll hear activity on those frequencies is if you're right outside the place that uses one or a construction company is using them within a block of where you are. As for the frequencies labeled fire, police, and public safety, those are all in the frequency areas where you will often hear public safety communications. It is true, however, that other land mobile users can use some of those frequencies as well.
