I don't think it's a secret that many women will go out with a man they are (not) attracted to rather than spend another Saturday night at home. In some instances these women see qualities later on that they admire in these men. In other instances the date was simply to fill up an empty calendar spot and the women have no intention of allowing a relationship to formulate beyond a "platonic friendship."
Men by contrast will only ask out women they (are) attracted to for the most part. Not many guys would consider spending a couple of hundred dollars on women they aren't considering as relationship material or a sexual conquest. Attraction is important.
Last but not least sometimes a woman's friends will encourage her to give a guy (a chance) if they believe he is "nice". They are prompted to look beyond attraction to consider other qualities.
Author Lori Gottlieb wrote a book titled, ("Marry Him: The Case for Settling for Mr. Good Enough.") Can you imagine the same book written for men? Not likely. I've never heard of a man urge his friend to go with a girl simply because she is "nice".
As far as women using dating sites for a "free" night out it can't be avoided. The majority of the time a man is going to at least pay for (the first date). If he determines there is no "chemistry" between them odds are there will not be a "second date". Whether you are a man or woman the vast majority of people you meet will not lead to a "love connection". In many respects (dating) is on par with (interviewing) candidates for a job.