I've seen plenty of cis people be 'accused' of being trans over the years, however, so even then false positives must be so hard for your mother to deal with.
This is a ‘maximizing’ technique here.
Now the issue is yes, the availability of testosterone being used in micro amounts by some females to cosmetically enhance their look, will cause future issues.
Those very few females that are mistaken for males without the micro dosing of testosterone has been rather conveniently exaggerated.
And all any of those females have to do is firstly acknowledge that they have tried to appear masculine and have succeeded to themselves. And to the patient, talk to the patient requesting a female health care provider about the patient’s options.
Women being mistaken for being male is an age old occurrence. Most women I know, and as my experience as a girl, deal with it and don’t take offense. Usually hearing a female voice combine with other sub conscious cues such as gait, hands etc will quickly dispel any concern.