Thinking about how, like ... if you want to have demon girls, and you want to reference existing demons, then you have the entire canon of demonology to go off of. And they're all in the public domain! Yeah, there's Lucifer (girl). Yeah, there's Asmodeus (girl). Yeah, there's Stolas (girl). The Lesser Key of Solomon alone contains 72 possible (girl)s!
With robots, however, it's different. There are in fact relatively very few robots in the public domain, (girl) or otherwise; there's no "greater canon" from which you can draw. Like what robots are there in the public domain? Quik and Silva? Tik-Tok of Oz? Fucking Pinnochio? Maschinenmensch from Metropolis isn't actually in the public domain in all jurisdictions. By Talos-from-Greek-mythology this can't be happening! Nor is there, like ... an equivalent of the whole "demons are from Hell/the Netherworld/whatever" thing for robots, they don't have a fixed origin or setting.
Basically, you pretty much have to create your own characters and the situation for them to be in. Which, I mean, that does have own advantages! But preexisting recognizability is not one of them.