You're making an apples to oranges comparison. If you can send a signal via a radio between continents, one can send a podcast using that signal with zero infrastructure between the sender and the receiver.

A podcast is an audio program delivered over the internet, which requires quite a bit of intermediary infrastructure regardless of the layer 1 medium.

When you deliver the raw audio over RF, it is called a radio program, which is what CBS has stopped broadcasting.

The throughput and bandwidth necessary for "podcasting" is many times greater than simple radio