What do we call the Internet, newspapers, TV and radio? They are the “media” when grouped collectively, as in “media reports say the war is going well.”
In formal language, a single newspaper might be called a “medium” but the term is convoluted and most people will not use it. No one says “I read the medium this morning and rain is expected tomorrow.”
For our purposes “media” is a collective term that describes more than one communication outlet or mode of contact while a “medium” is someone who purports to see the future.
In a similar sense, today we send out news releases and not press releases. Why? Because most releases are intended to reach media which have no presses.