I'll be talking about sex trafficking, racism, slavery, transphobia and sexual assault in this reply.
This stems from the late 19th century moral panic around what was called "white slavery". The term itself was obviously alluding to the widely held belief that enslaving whites is somehow different (implicitly worse, more shocking) than enslaving people of colour. It's an innately racist term and was all over the newspapers.
There were unfortunately stories of young (white) women trafficked in much the same way they are now (many documented cases had a "lover boy" scheme or a female accomplice meant to give a false sense of safety, where the survivor was kept in place by isolation and an attachment to their captor as much as by force). Typically it was women from the underclass trying to escape intolerable labour conditions, but their whiteness made their victimisation a threat to the hierarchy all the same.
Affluent women were not being kidnapped and locked in a room especially often, then or now. Often the focus was on the aggressors belonging to othered populations, for example Italians, so not only is the common narrative sidelining the more common victims of trafficking, the coverage was used to apportion blame to groups considered undesirable.
Today, this takes the form of disproportionate hand-wringing around "grooming gangs", where the narrative centres a supposed ring of immigrants abducting and raping white girls. The victimisation of children of all genders and races by white men and sometimes women in power is, of course, ignored. 'Sex tourism', which is often nothing more than a raiding party for white men to exploit and harm women and girls of colour abroad, is ignored. Systemic abuse of people hired to help around the house is ignored. Taking of passports on false pretences for purposes of forced agricultural, construction or sexual labour is ignored.
Under patriarchal white supremacy the white woman (who is not trans and has never sold sex, of course) is feeble – a guileless, wafting piece of tissue paper easily snatched up and brutalised by whichever group you've decided are 'the problem'. Any defence of, say, immigrants, to the fascist's persecution complex means you're personally selling their daughters to the roving gangs they've made up to get scared by. You can't argue with it in a way that will convince them. It's by design feverishly emotive, it's frantic, it turns the rational brain off.
Exaggerated threats to white women and girls are a basic building block of white supremacy. People need to stop listening to those fucking true crime podcasts, because of the above, AND because of how they invariably retraumatise the families. Not everything is everybody's damn business.