A meme does not create facts (and usually distorts them to make point, which is usually wrong).
If one looks up just Wikipedia (I know, not perfect, but still a minimally trustworthy start), one sees that, while crime, and violent crime in particular, has been steadily dropping in New York (so that it is now one of the US cities with the lowest crime rates - so why use it to make a point?), It still had 290 homicides in 2017, down from 306 in 2016, with a rate of 3.4 per 100,000, while London had 110 homicides in 2017 and 130 in 2016, for a homicide rate of 1.6 per 100,000.
https://en.wikipedia.org/wiki/Crime_in_London
https://en.wikipedia.org/wiki/Crime_in_New_York_City
We are nowhere near being the same and New York is still twice the homicides number of London.
So where does this sudden concept that they are the same comes from? It comes from statistics from the first three months of 2018 only. Statistically, this means nothing. You may have an unusual low number in NY or an unusual high number in London - or a combination of both - that will resorb itself after the whole year is over, or not, as 2018 as awhile could be a statistical anomaly itself. But a three month period, or even one year, completely out of norm does not mean anything in the statistical world - nor does it factually prove any point on a given subject.
https://www.usatoday.com/story/news/world/2018/04/03/londons-murder-rate-higher-than-new-york-citys/480860002/