>And prior to 1920, you could buy guns at the store with cash in the UK. Gun control didn’t exist in France until 1938. Yet the homicide rate of the UK was lower than it is today
According to the graph it wasn't. It was 0.8 and higher between 1900 and 1960, 0.7 in 1962, had a rise in the 70s and 80s, and is historically smaller than 1900-1960 today at 0.5 (since 2012 or so) while still not having the death penalty.
Which chart are you looking at? The fifth chart in the page shows the homicide rate of England at under 1 per 100k in 1900, and over that from 1990-2010. World Bank data says 1 per 100k in 2017, and there has been a spike in the UK last couple of years. 0.5 in this decade is almost certainly incorrect.
If your point now is that the murder rate didn’t go up after getting rid of the death penalty, that’s probably true, but a different argument than you made previously. (We should keep the death penalty because some people deserve to be executed for their crimes. But death penalty versus life in prison probably doesn’t serve as a deterrent effect that would lower the homicide rate. It’s a moral rather than utilitarian policy.)
According to the graph it wasn't. It was 0.8 and higher between 1900 and 1960, 0.7 in 1962, had a rise in the 70s and 80s, and is historically smaller than 1900-1960 today at 0.5 (since 2012 or so) while still not having the death penalty.