Paul Erdős
Of course, I can't deny such a device has practical value, I recall years ago about being somewhat mortified after having been at work for some hours and realizing my zip was down. In the meantime I'd walked from home onto a busy train and then walked some more to my office. Did I do it up at home, or when did it come down? There is no answer.
Then there's the problem of zipper creep, one recalls doing it up but the latch that locks into the teeth doesn't quite catch. This leads to continually-checking anxiety until one ditches the pants.
Zippers and I have a fraught relationship which I've mentioned in HN before, here I'm not only taking in connection with pants but generally. They break or slide undone unexpectedly, the teeth pull out, they inexplicably jam and cloth jams in the teeth not to mention the occasional harm they cause to one's person. Buttons may be less convenient but if one comes undone at least the rest don't do so in sympathy.
Maybe they should do something more discrete, like a vibrate function.... heheh.