Hacker News Reader

The README [1] says it is using data from OpenStreetMap, fetched with the Overpass API.

Yep, saw that. Then I wonder: why are those attributes (seamark:light:{sequence, range, colour}) filled more often for lighthouses in Europe?

OpenStreetMap in general seems to have way more contributors from Europe: https://www.osmstats.neis-one.org/

But in this case perhaps much of that data came from a data import that didn't have compatibly-licensed data for the US.