Even though zips have been around since T-rex roamed the earth, why can't they design ones which don't trap the fabric and get stuck? The big offenders are those on sleeping bags and raincoats.
And zips that look EXACTLY as they did when you last did them up, but now the tab goes up and the 2 sides of the zip fall open like they've never met. And it will never work again. For NO REASON.