The problem is actually somewhat different. In the casino case you need to compare every person to a relatively small set of "targets". In this case you need to

The problem is actually somewhat different. In the casino case you need to compare every person to a relatively small set of "targets". In this case you need to identify people who are breaking the law, then you can save that clip and you need to identify it against all know people. The casino case doesn't know if a person is "interesting" until they perform the match. In this case they know that someone is "interesting" right away. Then they can take more time and effort to perform the match, including falling back to humans. It probably still isn't easy. You will still have "unknown offenders" that are not matched, but that probably isn't a big deal as they are effectively a false-negative which probably isn't a major issue in this context.