They don't. It's all scripted and produced like theater at some corporate headquarters fifteen states away. No one actually knows aunt Ethel because she doesn't exist. And then it's sent out to the thousands of stations all around the country that the corporation owns and operates, to be played as "local radio". And even if a live human sits at the mic, he/she has a play list that can't be deviated from.
Owning a radio station now days is like owning a car wash. You just maintain the equipment and collect the money.
Jolly good, there must be many Texan octogenarians very disappointed that their request is played in Montana