The "It makes people paranoid" argument is nonsense in my opinion.
I recently told someone that the military in Germany should provide separate housing for female soldiers (They should already have it, but apparently they only have separate bedrooms) to keep the number of soldiers stable after nobody is forced to serve, anymore. Rapists are a very real danger in a male dominated "profession" like this, and certainly keep many women from entering it.
And he said "Oh no, that would look like the male soldiers are rapists". Yeah, right. Let's endanger women for the sake of making it look like everything is okay when actually it is not.
The reason why those parking spaces are not terribly useful is that nothing keeps men from going there and attacking the women parking there. Maybe even on purpose because they know there are women there!
The only advantage is that women have to walk shorter distances, so ... probably if you have a "risk per metre walked" that helps reduce risks of attack?
A separate garage where the entrance is controlled so that only women, girls and underage male children can enter would be of more use, but would cost a lot more money than just putting a sign there, so I don't think it will happen.
At the moment, if I were a politician, I would not choose to spend money on women only spaces. What use would it be to spend millions for a women only garage when it might next be decided that men who identify as female (i.e. all men who want to) can enter, too? Might as well use the money to hire a couple of guards.
Considering that the danger of acquaintance rape is much higher than that of stranger rape ... I am not really sure we need those separate parking spaces, anyway.
The money might be more effective when used for a education program that teaches girls about abusive relationships, how to get out, and how to avoid getting into them in the first place.