The UK is also an island and isnt neighboured by some of the most violent third world nations on earth. Isnt UK gun crime at its highest rate for over a decade as well? Our knife crime is basically the mirror image of the inner city US gun violence.
In the same way some parts of the US (ironically the cities with the toughest gun laws) are responsible for a huge amount of the gun related homicides.
Difference with knives is you cant use it to mow down a whole office. Or kill people driving by.