For instance, I just found out that Norway, for instance, also has a monarch. So does Sweden (?), and several other countries. But they — the Nordic monarchs — are unheard of in my country, and don't seem to have the same level of influence internationally.
Is that your experience as well?
(FWIW, my country was a former British colony but the British royalty is NOT my country's head at all).
I imagine the reason is because the Queen is part of the national identity of the UK, much more than the other European countries.
Millions visit London annualy to visit Buckingham Palace - the Queen is a symbol of Britain.