To this day, Bill is unwilling to see his victims as human beings at the time he murdered them. Taking that leap into the land of empathy is just too big a threat to his cognitive schemata.
So he can’t see his victims as good people or mothers bc it goes against the reasonings he did what he did bc they were “prostitution whores” who were already putting themselves at risk being on the streets. He’s unable to see them as victims bc he’s made his mind up that they weren’t going to live long anyway or likely conduct petty crimes so why would he see them any less than trash on the street