The UK is definitely a special case cf. the rest of Europe. For one, there is common language to consider. Secondly, it appears the UK makes up the next largest

The UK is definitely a special case cf. the rest of Europe. For one, there is common language to consider. Secondly, it appears the UK makes up the next largest userbase after the USA. It is as if to say 'why separate Canada from the US'. Similarly, NYC and SF are the prominent start up areas. Knowing who is in and out of these has uses. My take was that the OP would like to do every country, but obviously must limit numbers to something sensible.