There's a big difference between carrying a knife to fit a carpet and carrying a knife to spill someone's guts all over the f***ing floor!
And no, you don't send someone down for ten years for carrying a knife with no malicious intent, arresting bob the chef on his way to cutting up some steak is completely different to arresting a gangster on the street FFS. And if that's your major concern, how about a knife license, that would be too hard I take it?
Ok, so if your only concern is the route cause then how about more effort in to tackling gang culture, there's a start?