I think we are getting mixed up talking about ideal situations here.
Fundamentally speaking, would it be “ideal” to offer only classes covering shooting techniques, applicable to all, equal in most if not all respects? Sure it would. I don’t think anyone would disagree that the fundamentals of self-defense; mindset, awareness, and sound application of the basics of marksmanship combined with reality based vice square range scenarios, are not only vitally important but transcend differences in sex, background, etc.
However, it is important to remember that quite simply the “ideal” does not generally exist. For example, considering the obvious physical differences between most men and women, a course of instruction must naturally differ from student to student, if only on the most basic technical level. It’s not that this can’t be overcome by an adroit instructor, it can of course, and often is. But there’s more to it than that.
Basic instructional technique for example speaks about the impediments to a student’s ability to learn, or put more simply, what motivates a student to learn. Dozens of subtle things, even among very similar students, such as: background, types of learner, beliefs, etc.. force the instructor to tailor every facet of instruction so that all the students get something out of it. These subtle differences can sometimes drag the progress of a class to a snail’s pace, and this is in a class that’s basically the same such as a group of young male military members from the same unit.
In a class where the student spectrum varies much more widely, these differences become less subtle, drastically effecting the course of instruction, sometimes critically so for certain students. A student first and foremost must be receptive to learning, and there are women that feel uncomfortable (at least until a level of proficiency is obtained) around male students, teachers, either or both. To force this standard as the only option means that at worst, some women will never seek training or will get less from the training, or at best, they will attend and genuinely try but overcoming their preconceptions will unfairly take up the instructors time and/or attention.
Quite simply put, equality (outside of true equality such as the inherent rights of self defense, liberty, etc..) is a myth. The comments above about FORCED segregation vice OPTIONAL segregation are absolutely correct. To optimize the training, it behooves the instructor to attempt to address some of the impediments to learning before training even starts. If a student can choose a female, senior, military, police, etc. only environment because that’s what they’re most comfortable with then this makes the likelihood of actually LEARNING the course of instruction even greater. That there COULD be some benefit from a different course of instruction (more "high-speed", co-ed, male vs female instructors, etc..) is irrelevant if the student never really overcomes the initial impediments to learning.
"A ship is always referred to as she because it costs so much to keep one in paint and powder."
-ADM Chester Nimitz
ETC(SS) Phil McCrackin