Why do they call it a "Television Set" when there's only one?

It is like ‘chess set’ which refers to the board and the pieces. A television set contains a tuner a display and speakers. Television can mean television programmes or television transmission ‘television set’ makes it clear you are referring to the receiving equipment.

I agree with @flutherother. It’s a set of components. When the term ‘television set’ was getting off the ground the key components would be the set of vacuum tubes, including the picture tube.
Also the name rather certainly derived from the predecessor ‘radio set’ which again refers to the set of components for receiving and demodulating radio signals.

From what I know about it, It originates in how the original products came to merge back in the early 1900’s.
The earliest televisions by Baird in the UK were radios with the addition of a television device consisting of a neon tube which was rotated to create scan lines.

The “Set” consisted of merging the various components together.
One model contained a televisor only. One model was the radio part only.
Another model contained the televisor and a loudspeaker.
Hence a “Set”

@blueiiznh hit the mark and is completely correct. When I was growing up televisions were very expensive and always black and white. They came in large consoles with frames around the picture tube. Inside were a number of vacuum tubes that ran all of the functions from RF amplifiers in the tuner to triode tubes for the various voltages need to power the other tubes. A 26” size was a later development and even more expensive. I am pretty sure that our first television was a “huge” 21” (measured on the diagonal) display.

Also the first remotes were sonic clickers that produced different frequencies to change channels and raise or lower volume. Of course we never had a remote, that was for rich people.

Today most people drop the “set’ and refer to it as “the television,” the TV,” or ”“the telly.”

I’d add that radio receivers were originally referred to as “sets” as well, long before television was invented.

That makes no sense. A lot of them don’t. A “pair of pants” but for some reason it is a “shirt” not a “pair of shirts”

Perhaps, and this is stretching it, because pants have two legs. OTOH, no one talks about a pair of bras.

Nowadays, most people say simply “pants.”

So many things are made up of different components the same way a TV is, but we don’t attach the word “set” to them. There is nothing confusing about calling a TV just a TV, on the other hand, the term “TV set” obviously does. And it is not necessary.

@flo “So many things are made up of different components the same way a TV is” Sure there are, these days. It’s utterly mundane these days to have several million transistors in your computer CPU, and several dozens of highly complex parts in your ipod.

Back when ‘radio set’ and ‘television set’ were coined it was a set of exotic electronic parts. You could look at ‘em all day and not know a bit more about how they work, they’re mysterious. There weren’t a whole lot of things besides an automobile that ordinary folks had in their lives and were as complicated.

How about a reference to a theatrical stage ‘set’ ?

Both radio and television are stage sets on which unfolded the dramas of a great story, or the world’s news.

All that’s so easy to take for granted now as we have dozens of cable channels and bagillions of internet vectors of drama and information.

@dabbler That explanation doesn’t do it for me. It is one item, no matter how long ago it was invented, how complicated it was or wasn’t, .... You could call the components in a TV “a set of components” I guess, but the final product is one “item” not a “set of item”.

Some of the web flotsam I perused suggests that “radio set” comes not from household / commercial products, in a nice cabinet, with standard-size antenna.

Instead the term is earlier used lots of maritime and “ham” radio systems, which which were made of separate functional components connected to do what they do.
[ power supply, antenna appropriate <- that’s still external in a lot of cases,

The earliest ‘radio set’ were a crystal and a wire-coil tuning apparatus.
and for receiving: radio frequency tuner, sound amplifier, loudspeaker or headphones
and for transmission: microphone, voice amp, radio signal modulator, radio carrier frequency signal generator and broadcast amplifier… ]
In my opinion, radio sets like those deserve the term.

I’d agree that ‘TV set’ is superfluous currently because “TV” says all you need to say.

Cable “TV” programming doesn’t use any of the television parts of the set if you have a digital connection like (DVI or HDMI) from the cable box.(subsections like broadcast signal tuning, Image detection and image reconstruction), and internet programming (e.g. Netflix or YouTube) is digital from your computer to the “TV”.
When we’re watching digital programming, we’re just using the display.
It’s a “monitor” most of the time for a lot of us.