@EllenLRipley I have never heard of a woman 'flasher'
Then that's just you. I can assure you that women do flash and I have seen women flashing.
Is it possible that you don't hear of women flashing because it isn't reported? The overwhelming majority of people (myself included) would frankly not care if a woman flashed and I would never bother to report this, but if a man flashes, then at least some of those incidents would be reported to the police.
Women "flashing" generally means exposing tits to a receptive audience or "mooning" neither of which are crimes.
Women could also expose their tits or arse to people, or an audience, who are not receptive, and therefore, that would be a crime (but again, rarely reported because almost no one cares).
The police are currently searching for a woman who flashed her tits at the 12th July parade, so clearly it does happen (but personally, I wish the police across the UK would investigate real crimes instead).
If you know of women who've exposed their vulva/vagina and masturbated "at" people please add a link as I cannot find anything at all.
I'm not sure if you're being obtuse, because clearly that does happen.
I will not be providing links because it likely violates the Terms of Use, but just to pull one example off my head... Shell Jubin in the 5th season of Big Brother would routinely run around naked on TV. One day she decided to use the lawn mower naked. On another occasion, she was standing with a towel wrapped around her, then exposed herself and made the "woooo!" noise when she saw a housemate.