That's question requires an intricate answer: "It has to do with the fact that a Television has a screen while a radio doesn't. Also, a radio is one piece, while a tv is usually more. Now, how does this relate to your question? This is just the beginning. The resulting reason is to advanced for me to explain here."
There. Did that (not) answer your question?
Now,
In a world with out walls and fences, do you really need Windows and Gates?