I suspect that you don't know how to use them properly.These should be banned under international health and safety law!
They change size every time you use one, they have a tendency to 'slightly' open when you are using them and give you grazed knuckles, or worse, for your troubles and the damned worm decides it's not going to turn without a great deal of effort from your finger and thumb!
I have only ever had good quality ones, (Bacho, Draper, Hilka, Wera etc even snap on), and it happens with all of them. Oh, and they also round off the nuts nicely over a period of time.
Watch this and this.