The 1-10 score is not perfectly objective, it is after all measuring ideological concepts which are highly abstract, but it is subject to objective measurement to some extent. You can measure and compare what percentage of the economy is controlled by a centralised govt. and what percentage is in the hand of individuals. There are statistics that can be used to compare one country to another, eg: public spending as % of GDP.
The measurement of personal freedom is even more difficult, but not impossible. This scale attempts to standardise it, based on historical examples.
I'm sure somebody else can do better, but my point remains: political spectrums and labels that change meaning every 30 years are only useful as tribal siginifiers, just like football teams. They are not useful for political science and should be rejected.

