Western European cities have been getting more violent.
And from what I read, NYC is exceptionally safe for a US city, and London is exceptionally unsafe for a UK city.
Overall crime and especially violent crime is falling in the UK but there are some well publicised hotspots - phone theft, shoplifting
(I'm particularly unsurprised that they'd get confused about _London_, because, well, what is a London anyway? https://en.wikipedia.org/wiki/Greater_London . Even _human_ writers sometimes get confused about stats for London.)
It seems unlikely that this pattern of homicides would be explain by differences in general government policies between the U.S. and UK, such as healthcare policies.
Social media tends to make people _feel_ like there’s a lot of violent crime.