There is, quite fortunately, a rather large group of women who fall into your category 'A'.
Where I went to college there were several large multistory dormitories on the campus property that sat on a hill. Even the lowest one on the hill was relatively higher than most of the development on the campus around it; and of course as a high rise (10 stories or so) the vast majority of the rooms were well above anything that could have blocked the view into the room.
To make the setup even better, just off campus was a large residential neighborhood that sat on another hill even higher than the one on the campus. There was the obligatory 'fraternity row' right across the street from the campus, and as you got farther back into the neighborhood there were several multi story apartment buildings; most were no more than three stories, but as luck would have it there was one that was seven stories and I lived in that building on the seventh floor in a room directly facing the lowest of the four high rise campus dormitories...and the windows of that dormitory were almost directly facing my building.
The result was that I could see into about 90% of the rooms in that dormitory, and with my excellent angle in about 75% of the rooms I could see the whole room from the single window that each room had all the way back to the single doorway that went into the interior hallway of the building. About the only thing that I could not see was a very small piece of the room immediately underneath the window itself, which for the most part was where the students would put a desk so that ended up being really irrelevant.
I really have to kick myself because I went through my whole freshman year oblivious to the visual extravaganza available to me. But in the summer between my freshman and sophomore year I recall one evening just gazing out my window while studying and realizing that dimly, in the distance, I could see what I thought might be a naked person walking around in the room. Quite too far to make out any details - not even the sex; but it got me thinking, and within a week I had a VERY nice pair of high powered binoculars...and the rest is history.
Over the next three years I saw everything you can possibly imagine might happen in a college dormitory. Very quickly a naked woman became 'plain vanilla'; something you could easily see many times each night. What you really spent your time looking for was at the very least someone you knew, perhaps from a class; throughout the years I found several of those and enjoyed their nakedness, and on two occasions in that first year of voyeurism I found two girls I actually knew personally. Unfortunately they moved into apartments the next year, but still, it was quite a thrill to have lunch with them or study with them all the while knowing exactly how nice they looked totally naked. Of course the best find was actual sex; while as you can imagine it took place quite often in a dorm that large, sadly most of the folks who were 'getting busy' did so in low or no light, but even so I would catch two or three really excellent sessions a month. And once, only once, I caught a foursome, complete with partner switching
I spent untold hours with my binoculars, but for any given evening it was really not much time at all; it only took about five minutes to scan the whole building to see if there was anything interesting, and each year I would get to the point where I could remember where the 'best' rooms were which would last at least the whole quarter and sometimes that whole year. So I might, if I really had nothing to do, look as much as twice a night - but more often than not I was busy doing other things and most nights would pass without ever checking at all. The only serious amount of time I spent would come when I found something good while scanning
Keep in mind, too....these were
college girls. They were all in the best age range for this type of activity - late teens to early twenties, with a heavy percentage in the late teens due to the fact that most people only lived in the dormitories their first or second year, so the majority of the women I was seeing were eighteen or nineteen. Just PERFECT. Of course not all were attractive...but in such cases, I'd just scan right past just the same as if it was a room full of just guys.
So, back to the question the OP posed: These girls were TOTALLY oblivious. Part of it was their age - too young to know better - but in my opinion the largest factor was that if they looked out of THEIR window, the nearest window they could actually see into was so far away that the unaided eye couldn't make out anything, so of course they assumed that the reverse was true; and as far as someone using binoculars or some other device, what were the odds, right?
As it happened, they were very good odds indeed