Hi!
I saw that the “Tag:barrier=border_control” has not been adapted for quite a while. It would definitely be necessary to include a differentiation between “international border crossings” (all international travellers can use) and “local border crossings” (not open for all travellers, only for local people). This is particularly true for border crossings between EU Schengen and non-Schengen countries. See the discussion here:
https://wiki.openstreetmap.org/wiki/Talk:Tag:barrier%3Dborder_control
Thanks for starting this process!