The problem with experts is that they, by their nature of being experts, dont know or remember that not everyone knows that important detail, that makes the Job that they are doing easier or safer or more stylish. When a non-expert is put with an expert both will learn, the expert will learn more about his /her craft and the novice will learn the simple stuff. Youre not really a master of anything until you can teach it.
On television you need to find a person with personality to show stuff to the members of the public, now if you are unlucky the expert will be as dull as dishwater, you need pupils with a back story or personality, or if the expert has a personality (for example Dave Budd) then you need pupils who a bit mouse like.
Its only entertainment, its not like it is real life.