It is almost certainly true, given that the number was "nearly zero" in the past and nonzero today. At least, the number who were willing to take the risk in public was nearly zero.
I would need somebody to present me with data to justify a claim that it's unique to girls. Most of the pearl-clutching surrounding trans identities is about trans women, who are supposedly committing all sorts of horrors like lurking in bathrooms and dominating women's sporting events.