tim's answer already covers the Press Freedom Index methodology.
I'd like to add that for the United States the significant component of the result is the abuses score of 37.40.
This is a fairly large number: the second highest among the top 50, after Denmark (which has a score of 45, apparently, due to the murder of Kim Wall in 2017).
US Press Freedom Tracker lists 122 cases of abuse in 2018 including:
- 42 physical attacks;
- 26 subpoenas/legal orders;
- 11 arrests;
- 4 border stops;
- 8 chilling statements (6 of them from Trump).
As far as I can tell from the methodology, the last category is not included in the abuses score:
which translates to:
scoreExamination = 10 * log(90number of deaths + Coefficientinumber of imprisonmentsi + 10number of kidnappings + 5number of "media whose material was seized"1seizures + 3*number of exiled + number arrests + number assaults)
(1 Not a perfect translation.)
If the US had the lower abuses score its overall score would have been 20.32 (28th place, just behind Slovakia).
As the abuses score isn't weighted to population, it isn't surprising that the US scores worse than New Zealand:
- The US is 60 times larger than New Zealand in terms of population.
- The US is, by and large, a more violent country.
- The US has a huge news media industry. Wikipedia lists 15 nationwide networks for the US and 1 for New Zealand. I'm pretty sure that the difference is even larger on the local level.
Even on a logarithmic scale, the US is expected to have a higher score.
The rest of the score is based on the questionnaire and the factor of scale doesn't have such an impact on it.