But a per capita figure is diluted by how big of a tech sector that country/region has relative to the rest of its economy. The more people work outside of that sector, the lower is any per-capita figure from tech. Fewer lines of code written per capita, fewer bugs per capita, ...
The figure per invested dollar is much better: how many unicorns emerge per billion of investment money.
Those who chase unicorns are mainly investors (plus people who want to join startups that become unicorns). That figure is directly relevant to them.
The tech sector in the UK is pretty big but also massively finance weighted. And salaries a lot lower than the US so a $ investment goes further. At my company a few years ago our one developer in Boulder earnt more than our head of software in the U.K.
The figure per invested dollar is much better: how many unicorns emerge per billion of investment money.
Those who chase unicorns are mainly investors (plus people who want to join startups that become unicorns). That figure is directly relevant to them.