How come when women complain about anything, their complaints are

automatically found and just? but when men complain about anything that can be seen as sexism towards them, they are "whiners", "complainers", "people who don't have anything to do with their time" etc. I was reading a question about a man suing British Airways for a policy that treats all men as potential pedophiles, and one of the first responses was from a woman saying "Doesn't this guy have anything better to do with his time?" Suing is ridiculous". Another question about with someone pointing out another case of sexism against them , one woman simply called the asker a whiner with a "victim mentality". Thats certainly not the only time I've seen any men's problems just brushed away like this. I've seen it many times. So how come whenever women complain about anything, its a huge problem, but when men complain about certain things, they're whining losers?