There have been lots of schemes in the UK over the past few years where knives and other weapons could be surrendered. As with all these schemes, except in rare cases, it's just the law abiding that surrender their knives etc.
Usually granny will turn up at the police station with her deceased husband's boy-scout knife and so on.

Why would anyone surrender a carving knife or cook's vegetable knife ? Do the people that turn these in not prepare food? That's mostly the type of knife that seem to be in the press release photos to declare the scheme a success.

Flick knives have been illegal in the UK for decades. In the 50's and 60's nearly every schoolboy that went on a day trip to France bought one back with him. The teachers never seemed to work out what we were queueing to buy at the railway platform kiosk. Maybe they thought it was just cigarettes.

Most of these schemes are just an exercise to try to convince the media and the less cynical members of public that they are doing something, even if it's pointless.