Why don't some radio stations have online streams available?

Here in South Carolina, every radio station in the cities of Greenville, Spartanburg, Myrtle Beach, and Charleston offer online streams and I can listen to them on my desktop, laptop, or IPhone. But stations in Sumter, Orangeburg, and Allendale do not and I can't listen to them anywhere but the radio. Why could this be?

Either they don't have enough money financially or very few listeners to support it.

They don't want to spend the money on streaming. The fees can be very high.