Clipping Nails in Public

This is one of the most untoleratable thing for me. I cannot figure out why people can clip their nails in the train, in the office, in the book store or in a coffee shop. One clip after another, each crispy sound cuts through the air almost creating a paper-cut like sensation on my skin. I cannot explain exactly why it is so getting on my nerve. Clipping nails is supposed to be very private thing to do?