If you meant they are more complicated than gearboxes, then I think we are saying the same thing and either you aren't getting it or I am not doing a good job conveying it.
If you are think there is absolutely no analogy, gimme one and I can say the same for that too. If this was the case then, I am sorry but I believe that statement of yours was absolutely unthoughful.
Which is about the same degree of attachment expressed in the idea that a project manger can "shift" programmers into and out of pair programming mode the way one would work a stickshift.
Working habits are intensely personal, idiosyncratic things.
People -- by which I mean creative, productive, self aware & self-managing people; i.e. the only kind you should ever hire -- almost by definition don't like being pushed into working one way or another. Or being simply told what works best (because X or Y said so).
Working habits could be personal but there is something called as team work. You should also make sure the person is capable of collaborating. Collaboration does not always means attending meetings.
Some of the arguments down below read like: I tried driving in gear-4 and I disliked it, so I changed back to gear-5. Funny. Another one: One company forced me to drive in gear-5...again that company was plain stupid (or atleast the management was, for forcing you, in general).
Pair programming is effective when you are coding up while you are building the solution on the go. Its one of those sessions where its not possible to think up everything in your head. Ever had such moments where you didn't know all pieces of the puzzle? You can always say I would think up everything and then discuss in a meeting the whole solution. What if you went ahead and thought up the solution in a pair rather than discussing after you have laid out everything and then realizing you have to change it because you made a wrong initial assumption.
You cannot think up everything in your head (as another comment was there). Many times you do not have all the pieces and sometimes even if you have, you need to consult.
Seriously people, you are not getting the concept of pairing at all. Or I am just nuts.