supplying police with all citizens fingerprints and DNA would massively reduce the number of unsolved crimes

This might be overselling it. Only about a quarter of criminal offences are recorded by the police, and they already solve some crimes despite incomplete fingerprint & DNA databases. So even if expanding the databases meant the police solved every crime they recorded, the number of unsolved crimes would fall by at most 20% (unless there were a reason to expect reporting/recording of crimes to rise as well).