Good point uniquehornsonly
I spotted that, and wondered too.
You are absolutely right that a GRC is not required to change passport and driving license.
Either the authors are unaware, or they are actually saying that, having changed those documents first it's useful to be able to change your birth certificate to match, and a GRC is the only way to do that.
I'd disagree, if that was what they were saying. Changing a birth certificate to state X was born female, not male, on y date has always been a very disturbing legally documented falsehood. More so even than driving licences and passports, because it co-opts your mother into a lie. A woman gives birth to a male or female child. To alter the truth of that fact years after the event makes a lie out of an event of which she was the architect. It rewrites her experience too, without her consent.