[mschuster91]

> I don't understand what's wrong about using this information against crime?

Because demanding fingerprints from refugees but not Germans prejudices against refugees by branding them all as potential future criminals.

> Also I can imagine how difficult registering people who run from was is, surely there are cases with no documents, documents lost, abusive gangs registering people several times and claiming "borrowed cousins" as children they get more money for etc.

These are a negligible amount of cases. And especially not worth to destroy the right to privacy of the other 99.9999% of the population.