That surprises me as well! Particularly if it includes departments like ICE and FBI within that definition of policing.
I tried to search for the original source to see if I could find how they are calculating theses costs but didn’t have any luck.
I mention this because NYPD budget is often referenced as $6 billion, but that’s only operating costs, and the actual amount is closer to $11 billion (including fringe benefits like overtime and funding the NYPD pension).
With a 2020 GPD of $20,936 billion
Then 0.8% of that is $167 billion
If we assume that policing costs are more closely tied to population rather than GDP we’d expect that NYPD costs to be about 2.5% of national amount. That’s approximately $4.2 billion.
But NYPD costs are $11 billion, which is 6.5% of estimated national policing costs (for 2.5% of the population).
Admittedly, I can imagine that there are reasons why a big city area might have higher than average costs, but 6.5% makes me feel that the 0.8% of GDP might be either underestimating how much US spends as part of GDP, or calculating national costs using different methods for different countries.