Considering captchas operate by pushing the work of avoiding bots on your site (your problem) onto all the human users of your site, I think on the basis of that alone "anti-human" is warranted. Or "anti-social", if you prefer, which might better capture the fundamental problem with that aspect of it. That they proceed to perform textbook gaslighting on some of those people makes it even worse ("no, you didn't select all the buses in those images" but, of course, you did). Whether these things are necessary for it to operate is beside the point.