It’s also possible she hasn’t spent much time around devices that hum or buzz or whatever it does ... although I suppose there would be some cleaning machines and stuff in the vet’s office where she stayed.
I’m thinking of a floor buffer because she was out in the lobby “on display,” for most of the time, trying to entice someone to take her home.
She’ll come around. It may be six months or more, but that’s OK. I’m not going anywhere.