Why do you refer to the female candidate with her first name and the male candidate with his last name? The same thing regularly happens with Clinton. I assume the casual disrespect is not intentional but I’m very curious as to why this happens.
“Harris” is a more common name than “Kamala”, and “Donald” is a more common name than “Trump”. This is just my opinion, but I think Kamala is a more powerful sounding name than Harris, and that helps with her image as a stern prosecutor who wants to crush injustice towards women.
“Clinton” refers (in most people’s minds) to Hillary’s husband Bill moreso than Hillary herself. In her campaign, she leveraged her first initial for her slogan “I’m with Her” with the stylized right-pointing arrow in the H. For her, it seems to be her choice and more clear. For Harris, it just seems to be because “Kamala” sticks out in people’s minds more than her last name.
I think people tend to choose the more unique/recognizable name to call candidates by. For example, we also call Bernie Sanders by his first name more often than his last. “Harris” is a more common name than “Kamala”. “Clinton” could be confused for Bill, but “Hillary” isn’t going to be mistaken. I don’t think it has anything to do with the candidate’s gender.
Going to throw in a few other unique examples like how Alexandria Ocasio-Cortez is almost always called by her first and last name or the initials AOC. Similarly Ilhan Omar is almost always referred to by her first and last name.
The right loved to call Obama, Barack Hussein Obama with emphasis on Hussein to highlight how non-white he was, pin him as Muslim, and draw associations to Sadam Hussein. This was done to rile up their xenophobic and racist base.