They're wired up with a sort of redundant code so that if any two of the six wires break, the arm will still work perfectly, so that it's a kind of way of making mechanical things that's immune to at least some kinds of damage or errors.
The trouble with the kind of robots that industrial people use is that: there's a kind of engineering philosophy called "KISS," "keep it simple, stupid," and engineers in the space program and everywhere else are always trying to find the simplest way to do something because they think that will be more reliable because it has fewer parts, but in fact in the long run it's less reliable because each part matters too much.
And so, that's another direction to go which is not being practiced too much, but I'd like to see more people understand that "keep it complicated, stupid" is the right thing to do in the computer age.
-- Marvin Minsky, The Society of Mind CD-ROM
[This quote is in one of the videos in the Living Room scene, where he describes a remote actuator he built]