delve a little deeper....
Getting sex is important to many people. I don't even think there is a divide between men and women. Despite common misconceptions I think women can be a sexual as men and and desire sex as much as men. I think society still places chastity as a virtue on a woman and I think the fact that in the sex industry the workers are mainly women and the clients mainly men is more down to a cultural divide than a desire to get our ends away.
Men are less likely to be bullied or experience contempt for being sexually active with numerous partners. We still have a whole heap of derogatory words for promiscuous women (slut, slag, slapper, whore etc) and none for men. Being a stud or a player is something only ever attributed to men and they get their backs slapped jovially for it!
I think the fact that there are many many women who relish sex work or indeed non paid for sex or swinging demonstrates that women are as sexual as men and happy to indulge in emotionally meaningless encounters with numerous of partners.
However, it's generally agreed that it is much harder for men than it is for women to find sex. The huge number of female escorts there are over male ones, especially if you discount male escorts who only see men, it blindingly clear that the market for paid sex is mainly male.
The same goes for swinging sites, clubs and 'adult' dating sites single men always outweigh single women and I know from my own experiences as a single woman (or as half of a M/F couple) you can get sex very easily online and have heard many times over it is much harder for a single man. There are even sites such as XXXsexguides.com that review various adult sites to try and help guide men looking for that elusive shag to choose a site that contains genuine women.
I've heard men complain that on many sex or dating sites, the women are not genuine or they bottle out, or tend to want taking out and getting to know the man first or else they worry that the woman will want more than he does emotionally.
I know as a single woman a few years back wanting to meet with a woman for some sex it is very very hard. Even as a woman I found other women harder to find and more likely to want to play a long game of email ping pong. Same goes for finding couples, unless you are happy to do the meeting up and getting to know you think first. A nice simple process of swap a couple of emails, a phone call, come round, fuck is rarely that straightforward!
As for reasons, well, the ones I mention in my second paragraph to start with! Also, I think women are more likely to require an emotional attachment first before sleeping with a man, are more fussy (the old biological innate need for men need to sow their oats and women to require a good specimen for their eggs might be true!) and of course women are more likely to need to be safety and security aware. I know the problem lies with dangerous men, but in reality women are more likely to be nervous going somewhere alone with a strange man especially if she is too ashamed to tell anyone what she is up to and if there are more men out there looking she can indeed be choosy who she meets.
And that is why, my friends, paid for sex is as huge as it is. Those in the pay for sex world laugh at the outsiders view that men who 'need' to pay for sex are ugly, desperate old men with no social skills. We all know it's not the case. Every single escort I have ever met has talked about the kind, handsome, sweet, intelligent, funny etc etc men s/he has as clients. Men who seek professional services are indeed the savvy ones.