They don't, any more. That is, the TSA took corkscrews off the banned list about 2 years ago. And the corkscrew promptly went back into my going-to-cons bag.
That's in the USA, of course; other countries have their own standards. E.g., 3 years ago the Australian security people were not allowing duck tape onto planes. Really. I had my roll of duck tape taken from me, and put in a plastic bag and thrown in with the checked luggage, to be given back to me on the other end. (Which is better than what TSA does with confiscated items here, of course.)
no subject
That's in the USA, of course; other countries have their own standards. E.g., 3 years ago the Australian security people were not allowing duck tape onto planes. Really. I had my roll of duck tape taken from me, and put in a plastic bag and thrown in with the checked luggage, to be given back to me on the other end. (Which is better than what TSA does with confiscated items here, of course.)