These technologies are probabilistic with some nonzero chances of error which can't always be easily detected. These are implemented by people with some knowledge of the tech used (and hopefully the understanding of error), but are to be used by people who expect the output to be 100% true. I do not know how they would deal with tech errors which do not look like errors, but feel like there should be more cognizance about this and expectations should be set accordingly. Same goes for any facial recognition tech deployed by authorities.
[1]: https://en.wikipedia.org/wiki/British_Post_Office_scandal