You can make those rods bend any way you want. I purchased a professional set made very well. they were shiny brass looking, bent to the correct angle, and the handles were inside a small PVC pipe to eliminate friction, with metals balls on the end, I tricked many people that I could witch for water. Here in Florida, you will find water almost anywhere you did.
There is no scientific reason that this works with any success. It is just pure luck and knowing something about topography. and observation. What so you think would happen to those rods held level, out in a boat, on water. You think those rods might just spin uncontrollable Ok smart guys, why did the older generation use wood, and a particular wood, and it had to have a certain shape, like a { Y }, and when you found water, the the stick would bend almost straight down. If this part is true, why are the trees not bending their branches down pointing to water, but maybe they are. Just find the tree that is bending down, and you have found water. Now it is brass, steel, copper, coat hangers, what is next, plastic. How do you think it works, by lines of force, then why use wood. Do you think the lines of force might be concentrated inside metal pipe. Does it work with PVC pipe? Someone once told me the principle works on faith, got to have great faith though. Sometime back, someone offered a large reward for someone to find water with a reasonable accuracy, and it appears that no one has collected yet. I have faith, but not in every thing.
Believe what you want to believe, that is just life.
I fully understand your skepticism, I too felt this way once. You don't find six different lines, you did not know were there, in a 30' x 40' area, with luck.
I have never seen the Y shaped tree stick demonstrated, and have no idea if it worked.
I have seen many times, and personally used the wire rods with a very high degree of success, (nearly 100%). A much higher degree than "chance" could possibly ever achieve.
Make a set up, and walk through your house with them. After learning to keep your your hands level, and slightly lose, so they can swing, you will locate every pipe and duct under your floor, which you can, (especially if you had a basement, I know in Fla. it's not common), visually verify.
If you know where lines are in your yard, use some one who has no idea what is going on like a female, or child, to do the witching out there. They will locate them.
Another way, is to go where underground utilities have been marked for digging, and test there.
I'm no fool, if this was not possible, I would not bother trying to convince you it was.
Disbelieve what you want, but please don't do it on the basis of your assumptions.