They are costly, for one you have equipment cost which can run into the thousands, upkeep of that equipment, if you don't buy land and tower then you have rent cost for tower space, location, location, location, keeping unwanted people off your machine means more money on your machine for restricting access. Reason for restricting access is because you are responsible for any and all content repeated through your machine, which the FCC holds you liable.
They can be a challenge if you want one, just expensive for a hobby