If we take that the 'test accuracy rate' for (the general) you being able to tell who is transgender to be 99%, which is in and of itself absurdly generous given how many people are sure demonstrably cisgender women are transgender, with the rate of adults being transgender as being between 0.004 and 0.006, then the 'true positive' rate (the probability of A given B) is going to be between 0.30 and .333. Which means the 'false positive' rate is going to be the remaining.
Okay, I think I can see what you're saying now. If the base rate of relatively masculine cisgender females is much higher than the base rate of masculine MtF individuals, then the false positive rate will be high if you are using masculinity to sort people rather than something more reliable.
Unless those steroetpyically masculine markers are enough for you to believe they are trans women, as you have maintained.
I have not, and do not, maintain that adherence to feminine or masculine or feminine social norms ought to be factored in if you are trying to guess birth sex. There are far more reliable indicators of sex available, which is why there is currently a growth market for facial hair removal by electrolysis and facial feminization surgery, among other feminizing body modifications.
You claim that their word, their self-id, isn't enough for you to use she/her pronouns unless they meet your level of perception to 'pass' as cis women.
If by "use she/her pronouns" you mean at all times and places, then yes, I reserve the right to use the pronouns that make sense to me instead of the ones which make sense to the people being referenced, when having conversations in private. You have yet to convince me that pronouns are somehow correct or incorrect because of self-id, since I've used pronouns for several decades before even being introduced to the idea of self-id.
Let me provide a specific example, to show you what I mean. The woman on the right in
this picture goes by Seani and helps to moderate a
travel group for womxn. That's all well and good, but because he looks just exactly like a beardy bloke, I have trouble using his preferred pronouns when he's not around. Am I doing a violence?