Because you're not sleeping with men
Women aren't easily manipulated by sex. Men are. It's our Kryptonite.
And yeah, I think the "taking care of" aspect is interesting, but when you look at the stats for heterosexual couples, it's mainly men doing the "taking care of" which I think definitely admits that there is a gender stereotype still. In theory I always say I like women who pay their own way but in practice I never let them so I don't see the point. Every so often they'll pay but I always feel bad about it, and yet, should I really?