>>11782707That risk is per instance of unprotected sexual intercourse with a partner who has an STD you don't. The distribution of who has sex is different between straight men and women -- men's is more uniform while women's is more skewed. That is, there are a small handful of women who are "turbospreaders" and have contracted a large number of STDs due to their increased chance per instance of sex to catch them, and then go and have sex with many men and spread the STDs despite the fact that men are less likely to contract in a given instance. If we were to count how many infections these turbospreader "would" have if you could be infected multiple times, the number of infections between men and women would reflect the values you're expecting (though a supermajority of infections of women would occur in a small minority of women).
Also gays are whores and lesbians are prudes.