You're definitely right in that children are very different from another. In my experience, however, fear almost always comes from a previous bad experience or it transfers from other people. I've done the "first time at the hairdresser" with both of my children and they still love going there, ten years later. Back then, we took our time looking at all the tools and watching other people's hair being cut. With the permission of the hairdresser, I let them play a bit with the revolving chair. No talk about how it might hurt or anything.

In the story above, the only explanation I can think of is that the boy already had a previous bad experience with a hairdresser. (Didn't look like it but I can't be sure.) Even then, I'm not sure this was the best way to handle it.