With no clips to trade, I'm merely spectating at a tennis match, but I remain unconvinced that the UK response is in any way better.
In all 3 clips (your two, plus the parent's) what I see is that a person holding a knife is an immediate and real danger to anyone within 15 feet of them.
Also, if I'm seeing correctly, both assailants had already been pepper-sprayed, is that right?