Of course, on that note, we're forgetting that Wagner's NiS setting is basically the sexual revolution and government run amok. Where AIDS was basically a speed bump, STDs have been cured, and a 100% effective (non-permanent) birth control option exists. (Although I know some NIS authors went with settings where STDs still are around, AIDS still is a thing, and birth control isn't infallible)
You're still going to be stuck with the ones most likely to accept the more "demeaning" options as being the ones who are least qualified, at least initially. Assuming those people are capable of becoming qualified, and that they do so, then things begin to shift over time.
Which was a large part of the premise of Wagner's work if you look at it a little deeper. Since it demonstrates a shifting window of expectations. Particularly once you look at the "backstory."
Part of her justification for NiS was that the "window" had shifted so much, and so fast, that the "NiS Program" was needed to "prepare" the students for the new (nude, mostly service sector) work environment they were preparing to enter into. So that they could get over the "culture shock" experience while in school, instead of while in the workplace.
The most recent NiS stories have almost lost sight of this entirely. In Wagner's story public female nudity already was "a thing" out there. The "reality" of her setting is that most students would have likely already encountered a fair bit of nudity in their own lives, albeit most of it may have only been through the TV, if that, depending on how sheltered they were:
When the AIDS problem was solved, and other sexually transmitted diseases were also cured, the trend toward treating men and women differently still continued. One college started allowing the cheerleaders and pom pom girls to appear topless, then another required theirs to cheer in the nude. Women's professional sports competed in the nude, then as their popularity grew, so did collegiate sports. Women's sports which had previously been ignored were now filling stadiums, bringing new emphasis to the schools, and making real professional women's athletics profitable. Court trials failed to ban the practice, since it was bringing money and emphasis. Sex sells.
This spread into business. Young female executives made a much more significant impact when they left their clothes outside the board room, and used their advantages instead of demanding gender equality.
So at least in a "Strict" interpretation of the Wagner-verse, the Cheerleaders, and other (female) student athletes at school are probably more than fully aware that if they intend to pursue their athletic endeavors into college and beyond. They're going to be leaving their clothes behind after graduation, so they might as well start getting used to the idea sooner or later... (And raises questions as to what those High School Athletes would encounter should they attend a special "camp" sponsored by a given athletic program from those Colleges/Universities, at least so far as dress code goes.)
Likewise, according to that quotation above, it would seem that at least some of the "female role models" in terms of successful business executives and whatnot likewise would already be featuring more than a few naked women in it. So at least in terms of nudity, Wagner's NiS story existed in something of a "sweet spot" where Female Nudity had probably only "recently"(say, within 2 to 5 years prior to the Wagner story) been nearly universally adopted at the Collegiate(University for you international types) and Professional sports level, and was only really starting to make itself known in the business/executive world. As such the practice hadn't (yet) fully "filtered down" to society at large, or the service sector.
The 2 year number(for the "late adopters") is so that the Universities would have had at least one or two subsequent "intake cycles" where students were experiencing culture shock over the nudity thing, and for them to start pursuing efforts "to help address the issue" which opens things up for creating and introducing the Naked in School Program.
Basically, people in smaller(non-Uuniversity/college) towns "know" this stuff is going on, as they've undoubtedly seen plenty of evidence of it on Television at that point. But the odds of them having seen anyone practicing such things locally are slim to none. Likewise, it's still new enough that most national (service sector/retail) chains would be starting to become comfortable with the idea of pursuing a nude (female) workforce policy as chances are the first cases involving such policies would likely have played themselves out in court by about that time, and also would give them a chance to asses what other impacts may be on their respective businesses if they pursue it themselves.
NiS itself helps in some other ways too, by playing canary in the coal mine as it were, as it should flush out any opposition to it in short order. You get anecdotal evidence of this in Wagner's story, with her journeys into town and finding that Ice Cream Shop is "normal" on Tuesday, but has its servers undressing in response to under-dressed customers(that it is encouraging to be under-dressed) by Thursday. Likewise, Karen's discussion with her parents on Tuesday also suggests that her mother is likely to be going naked@work sometime "soon enough" so the nudity thing is filtering through society even without NiS becoming involved.
But that only involved the nudity side of the equation. The "sexual favors" isn't so explicitly outlined, other than it being included as part of the NiS Program itself.
Although it is kind of funny to note that many of the more recent NiS stories seem to be focusing on the imposed nudity from the angle of our own world. Rather than from Karen's construct. They still work as NiS because they have most of the relevant parts, but they're still breaking from the social construct of (young adult) female nudity being increasingly seen as an inevitable outcome that they need to be prepared for(and the impetus for the Program) if they intend to be more than "just a housewife."
Instead they're operating from the angle of the Program trying to turn the students into sexual exhibitionists in a social setting where Nudity has no real application in the real world, and that (women's) college and professional athletics are operating as they always have, rather than under the Wagner model as it were.