> The symbol ... is directly descended from the RAF

Aircraft roundels originated with the French Tricolore cockade. Concentric circles are used in many many country's roundels, and are far from anything particularly British.

I think perhaps your mistake was thinking that the description given was meant to be exhaustive?

It's as if I said "The American flag (composed of stripes and a blue corner)" and you were to say "wait, that's not exclusively American"

Yes but, so what?

Yes and the Kiwi roundel is directly descended from the British RAF symbol.

Which you can distinguish from all other roundels, by definition, or they wouldn't be useful things to have!