About a month ago I tried Overpass API to get the data for Thailand. It claims you can request up to 100 square degrees. And indeed you can do that but the data returned is incomplete. E.g. for a Khon Kaen Province bbox, an area of 1.5 times 1.5 degrees, I got 246,283 points instead of 333,074, 0 lines and 0 relations. For me: unuseable.