The border line here, does not match with the border on Google Earth, which itself (and OSM’s) border does not match with Google Maps. So I have 3 answers. The variation is over a mile (2km+) at one point, and a village as well as 2 peaks could belong to different countries, depending on the map used.
My question is, what is the source (or potential sources) of this data, and how can it be made more accurate, or proved that it is the correct of the three? Who (in governments and/or international agreements) holds this type of information?
To note, the borders from Google Earth and Google Maps seem to be displaying different data. One is the border marking the edge of the Emirate of Ras al Khaimah, and 1 is the national border. However, 1 of them must still be wrong, unless the thin slither between them belongs to another emirate.
One option would be one of the English language mailing lists, another might be the International Boundaries subforum at https://forum.openstreetmap.org/viewtopic.php?id=64941 (either German or English will work there), and yet another might be to try and contact who created or edited one of the nodes that form the border.
Looking at the history of the way http://osmlab.github.io/osm-deep-history/#/way/21105236
and it’s geometry changes - with the “Show More” button - shows that user Sal73x has done some refinements in the north in June 2014. No comment or source tag, so you might want to ask for the sources with a changeset comment.