yes we've had spikes of knife attacks over recent years, a lot of it is gang related, with kids stabbing rival gang members in tit-for-tat spirals of violence.
Knife crime in general is nowhere near as bad as it is in America (and of course as you point out you guys have gun violence on top of that), but the UK is historically a peaceful country and our tolerance of friends and family being murdered in the street is a lot lower than yours.
Well. Some of those chaps were carrying knives - without a licence - so we had no choice really.