I noticed pages which are places e.g. buildings, ruins etc do not have lat, lon coordinates despite existing on the page:
https://en.wikipedia.org/api/rest_v1/page/summary/Acropolis
https://en.wikipedia.org/api/rest_v1/page/summary/Antonín Dvořák Museum
it seems the summary endpoint only adds them if there are coordinates at the top of the page - it ignores infoboxes {{coord|...display=title}}
The handling should be updated. There are likely many impacted pages