Yes, it does seem to be increasingly happening. A family friend’s son was stabbed and killed last year - had an argument in a cafe with a couple of guys on the table next to them, and after they left one of the men stabbed him. You see strangers arguing over stupid things all the time - you’d never think it would end in someone dying.
There was also that story of a teenage boy randomly stabbed and killed by a stranger, who was another teenager boy.
It seems to be angry young men, always.