Pencils scare me. Mutable paper trails seem less than ideal. I think I prefer a pen along with an option to request a new form in the event of a mistake. Optical scan for counting along with a paper trail for random sampling. I don’t know the perfect system, but a dual recording mechanism for back checks seems better than just relying on paper or just relying on machines.
Regardless, this is actually the fault of the user rather than machines. As far as I know you can still get a replacement if you do this.