Individuals can be consistent, populations are not. Men as a group do not all behave the same (aka "consistent" for their gender) or all have the same expectations, just as not all women behave/expect the same.
There has never been consistency at a population level when it comes to how men and women receive advances from the other.
True, but there are norms and averages.
>What, exactly, are women supposed to explain to men? And why is it their job? (Honest question as I'm having difficulty seeing how this is supposed to work on an interpersonal level and no woman can speak for all women.)
I explained this in my original comment. Women should have a reasonably standard way of behaving when they are sexually attracted and a perceivably different way of behaving when they are just feeling friendly. And they ought to explain to men what the two sorts of behavior are, so men can spot the difference. I don't see why that is unreasonable.
I've already said why your position is unreasonable, but I'll say it one last time: These homogeneous populations with homogeneous behaviours don't exist. Even within cultures and within generations, behaviour differs according to lived experience. You will falsely rule people in as well as out if you rely on some kind of shortcut rule of thumb to indicate interest. This applies to both sexes.
If you start with the default assumption that women who are friendly are ... just being friendly then misunderstandings are far fewer. Most men who approach you are just being friendly rather than coming on to you. Do you require men to reassure you that they are not coming on to you as well? Most women are not into every man they interact with. It's not their job to convince you otherwise. It's your job not to assume.