There is a subtle difference between using a, the, or no article in this sentence.
Ads propelled radio and TV, why not education?
When used without an article, radio and TV are understood to mean the entire field of communication by radio/television. That is, the entire industry of radio and television programs, along with the devices themselves and the people listening to them, were propelled by ads. The speaker means something similar with respect to the entire institution of education, so this makes sense here.
Ads propelled the radio and the television, why not education?
There is a subtle difference here when you use the radio and the television instead of the phrases without the article. Here you're talking about the physical device itself, the actual radio device an the actual television unit. So the implication is that ads spread the popularity of the device and resulted in more purchases of the devices. This doesn't parallel as well with education, which is an institution and not a device.
Ads propelled a radio and a television, why not education?
This is simply incorrect; a radio refers to one single radio device, and a television refers to a single television unit. Obviously the speaker doesn't mean that ads propelled a single radio and a single television in any way. So this would not be said.