UK license plate spy cameras

Add this to inconsistencies I don't understand.  Google street view often gets lambasted for privacy issues.  That happens when an individual or a car license plate is visible.  Since these street views are one time images - one only gets captured if one happens to be in view of the camera at the specific time and place it happens to be.   Privacy commissioners, including in the UK, generally want faces and license plates to be blurred.  But the UK police get away with implementing a system where cameras log all car travel and keep records of where all cars are when they pass by each of the huge network of cameras for 2 years.  As Wired Gadget lab puts it:

UK police are on the verge of a a huge surveillance coup which will make 1984’s telescreens look as dumb and benevolent as a corner-store CCTV rig. Britain’s network of spy-cameras includes a fleet of Automatic Number Plate Recognition cams which read around 10 million license plates a day. These will soon be piped into one central computer which will compile and share this intelligence across the nation.

Remember: This isn’t being used to scan and log already suspect automobiles. It is recording the movements of every road user, whether a suspect, a criminal or an innocent traveller.

Perhaps I can understand a system that looks for license plates that the police are looking for, records that and alerts officers - but recording that info on every vehicle that passes by, and keeping it for 2 years is just wrong.  

Two basic privacy principles are that no one should collect more personal info than is necessary to do what needs to be done - and  any personal information one does have  should be kept no longer than it is needed.   I just don't get why these principles are not applied more heavily to government collection of information.