not only does the FCC differentiate between devices, they also differentiate between transmission frequencies. I know this from having hand held two way radios and also from back in the day of cb radios. it mainly comes down to money. In order to transmit on certain frequencies you have to pay the FCC for a license. They have spectrum open for public use, however, its the crappy end of the spectrum that is transmitted by line of sight only. B/c radio waves comprise a range of freq. they regulate them differently.