It’s already strange that it’s often accepted when women use the men’s restroom.

The other way around, a man who enters the women’s restroom is immediately labelled as perverted or predatory. Why aren't women held to the same standard and labelled the same way?

What bothers me the most is the architecture.
Men’s restrooms have open urinals that don’t offer full privacy (not even from behind).
Allowing women into this space is a clear violation of men’s privacy.
The fact that the line for the women’s restroom is longer changes absolutely nothing about this fundamental issue.

Imagine the reverse scenario:
Suppose women’s restrooms had open urinals and they used like "Urinellas" ( https://en.wikipedia.org/wiki/Female_urination_device ).
Would women accept men just walking in there?
Absolutely not.
It would immediately be viewed as a massive violation of privacy and rejected with outrage. Why doesn't this standard apply the other way around?

A "unisex restroom" that still contains open urinals does not solve this problem. In fact, it enables the violation of male privacy rather than fixing it.

The only fair architectural solution is fully enclosed, single-stall restrooms for everyone.

Don’t get me wrong:
If men’s restrooms consisted *exclusively* of fully enclosed stalls, I wouldn’t have a problem with it at all. In that case, everyone’s privacy would be preserved, and it would be functionally identical to a women’s restroom, just under a different name. In such a fair scenario, it would also be completely logical and consistent for men to be allowed to use the women’s restroom.
Unfortunately, that’s not reality. Most men’s restrooms have open urinals, and that is the crucial difference.

My appeal to all of you (including women):
If a woman enters a men’s restroom with urinals, address her politely but firmly.
We have to speak up. If we silently accept it, nothing will change. Only by communicating our boundaries clearly and respectfully can we see long-term change.

Important when speaking up:
do not touch anyone
do not block the exit (otherwise, you will immediately look like the aggressor).
do not yell

Stay calm
speak quietly

If she refuses to leave:
1. Do not argue
2. Get the staff/management (in clubs, restaurants, or offices, it is their job to handle this, even if security can sometimes be unhelpful).
3. If nothing happens: Ignore it or just use an enclosed stall yourself.

There are valid exceptions (e.g., if the women’s restroom is broken or locked), but long lines are not an excuse. If a woman needs to use the men's restroom, she can simply ask the person inside politely if it's okay to enter, and vice versa.

Context:
https://www.yahoo.com/entertainment/tv/articles/nicolas-cage-says-probably-won-190703040.html
https://www.youtube.com/watch?v=tyzq1WmZuCw