Basically, if you grow up in an area where it is normalised you are told by society that not having it is weird, dirty, and ugly. The difference is that men actually have dicks, so are in a better position to assess what the difference is. Meanwhile, penises are these alien taboo things for women that are off limits for much of their lives.

The women who grow up in these areas also internalise the beliefs about uncircumcised dicks being wrong. However, lacking dicks they remain more alien. Thus they more deeply internalise the belief and express it by perceiving uncircumcised as aesthetically displeasing and gross.

So these women are not particularly smart or self-reflective, and never realise that their disgust for uncircumcised dicks is merely a product of their upbringing and society, and they come to vehemently believe that their perception is the objective truth, never questioning why women in other countries are not campaigning for men to get cut out of disgust. A touch of xenophobia helps here.

Basically it boils down to: I want my kid cut because I find uncut dicks gross and what I feel is the absolute truth and ain't nobody gonna make me question that.

Americans do have a habit of becoming grossed out by stuff only because someone told them it was gross. It a great way to make money for cosmetics companies. Nobody was grossed out by off-white teeth until teeth whitening procedures were made available to the public, but once it becomes normalised perceptions change and few ever bother to question why they think and feel the things they do.