You have done precisely what I have had in mind to do over the last few years. To go out shopping with my friend Diana following discretely in my wake to observe what really happens. Your social experiment proves what I have known to be true in my heart, that despite the pleasantries we experience when out & about, where we are seemingly treated as any other woman, when no one seems to even notice our presence, it can be a totally different story outside of our peripheral vision or earshot. Well done and very well written.
But I will also echo one of your points that despite what you encountered, the world failed to explode based upon the reactions of a few bad apples (and one very bad & unemployed one). Those people are outliers, exceptions, they are NOT the norm. True, most don't blink an eye at a TG person in their midst. Those who do can be a very obnoxious minority. Still, this is precisely the reason I scoff at those who claim to pass because things like this DO happen in our wake. Even when I convey being out and no one gave me a second look, I'm well aware of the reality of what may be happening behind the scenes. It helps not to be delusional about this subject but it also helps not to care in the least bit.