The other thing was that these lambs were prepubescent, quite literally you have to fish the balls out. I saw the episode and it took one person to hold the lamb, one to hold its legs apart and one person using both hands to get the balls out of the body so it would be highly inefficient to add yet another person to this process to clamp and pull them off.
There are other ways to do this, just none of them do it fast enough. One method is to put a big elastic band around the scrotum and wait two weeks for them to drop off, the problem with this is that some of those lambs become mature in that time and then you get multiple Rams that end up trying to kill each other, one of which is likely an ideal breeder you need alive. This method supposedly only takes 2 people to do, however it takes 2 weeks to complete, where as biting takes 3 people and 2 minutes to complete so you've got the entire herd done before you've fully castrated your first lamb using the technological method.
Teeth do have some advantages here. Forget high-tech and low-tech, this is no-tech.