Comfort? Dignity? These are extremely subjective. Tons of people feel discomfort around homosexuals in their spaces, and for good reason: people want to avoid sexually titillating someone whose sexual attraction they do not want to invite or be a part of. And yet we all still change together.

But girls' & women's need and desire for comfort, dignity and privacy isn't just about wanting "to avoid sexually titillating" others. Often it's not about that at all. In fact, the way you've framed the situation - placing all the onus on the persons being viewed (in your view those who "titillate") and none on the viewers (who in your view are liable to be titillated at the drop of hat, or rather trou) - conveys a view of human sexual arousal and functioning that a lot of people would take issue with. And which comes off as puerile or adolescent.

The way you've framed this also assumes that most/a lot of people believe ourselves to be so highly attractive to others that we're convinced they'll get turned on sexually just by seeing or being in close proximity to our unclothed or partially clothed bodies. When, in fact, a lot of people have such negative body-images that they think the opposite - that other people will be repulsed by the sight of their naked or partially unclothed bodies. And when, in fact, due to age and general appearance, a majority of the population do not think we are likely to arouse the lustful passions of every Tom, Dick and Nancy we encounter.

Take age, for example. Most women "over a certain age" know full well that we are essentially invisible to "the male gaze" generally coz of our age - and that our age makes us unlikely to catch the fancy and stir the loins of lesbians and bi women on the prowl too. In the US, more than 60 million are over age 50 - and the majority of us would not list wanting to "avoid sexually titillating" others of either sex as amongst the top reasons why we desire and need the comfort & dignity afforded by sex segregation as well as by courteous, discreet behavior from all parties in shared toileting and changing facilities. Some of us wouldn't list it at all. Same goes for many older men. Honestly, a vast proportion of the population does not desire bodily privacy because we think getting a gander of our unclothed bods is gonna cause strangers to get "titillated."

You also are framing the situation as if girls and women are entirely analogous to boys and men physically and in terms of how we are treated in society. Neither of which is true.

In human cultures, girls and women's bodies are sexually objectified in ways and to an extent that boys and men's bodies are not. Moreover, girls and women's bodies go through processes and changes - such as menstruation, pregnancy, lactation - that male bodies do not. For both these reasons, many girls and women feel special discomfort at the prospect of being naked or partially undressed - and of having to deal with intimate bodily matters like menstruation and blood leakage, pregnancy vomiting, pregnancy-related issues like piles, miscarriage, post-partum or post-abortion bleeding, leaking breasts, flooding from fibroids or menopause, urinary or fecal incontinence due to aging, etc - in a room where men might be coming and going, some might look, leer and listen - and some might visit and linger in precisely for the purpose of looking, leering and listening (and sniffing too).

A significant percentage of the male population has one or several paraphilias. As a result, a good number of boys & men engage in voyuerism, flashing, public masturbation and are aroused by matters of female biology such as menstruation, pregnancy, breastfeeding, and female urination. Some men get off simply on hearing girls & women urinate. Most/many of these men typically do not ever escalate to physically assaulting girls or women, so they pose no safety threat. But still it's reasonable for girls & women not to want to be around them particularly when we are naked, partially naked and/or dealing with intimate bodily matters.

Similarly, many boys and men who don't have paraphilias, are not generally considered perverts, & never have and probably never will commit sexual assault, are nevertheless accustomed to using the toilets & change facilities at school, work and in public places to jerk off in. Tucking into the boys or men's room to "rub one out" in the course of a work shift or school day is customary behavior for a huge number of boys & men. It's perfectly reasonable for girls & women not to want to be anywhere near this activity.

When you scoffingly say

Comfort? Dignity? These are extremely subjective.

It makes you seem extremely naive about how some boys & men behave in loos, change rooms, locker rooms, hospital wards and other such spaces outside the home. It also makes you come off as very insensitive to, and dismissive of, the feelings of the bulk of the female population, and our need and desire for comfort and dignity. It's like telling people who need special accommodations coz of disabilities, Accessibility? That's extremely subjective. Accessibility to people in wheelchairs means one thing, but to people who are blind or visually impaired it means another. Then there's all those pesky people who can't hear... See, the complaints & issues the disabled have are all subjective. They don't even agree amongst themselves. If we take one group's subjective situation and feelings into account, where will it end? Best if they all just suck it up and make do with things the way they are.

Also, please provide some evidence for your claim that

Tons of people feel discomfort around homosexuals in their spaces, and for good reason: people want to avoid sexually titillating someone whose sexual attraction they do not want to invite or be a part of.

And in so doing, please specify the sex, age range, place of origin & residence, religion etc of the "tons of people" you are referring to. And their sexual orientation, or rather their presumed sexual orientation.