The function defines the shape of the kitchen utensil, yes. That's not a counter, those are physical objects. In software, we have far more flexibility as to what "shapes" are available.
Having a common interface for working with things is indeed why the flexibly-typed languages are popular. Everything is an object. You call methods on every object in the same way. You don't need to figure out how to interact with the network card, someone has written a library to make that into objects. You don't need to figure out how to interact with a file system, someone has figured out to make that into objects. Bringing up popularity of programming languages is an argument in favor of "'everything is a file' is a useful abstraction."
Either people will write FUSE plugins or they don't want consistent interfaces is a false dichotomy.
When you are interacting with programs, you use mostly keyboards and mice. Why not create a bespoke hardware interactions for each program so they can behave more like kitchen utensils? Deleting a file is a different action than creating one, so I should have to shake my computer like an Etch-a-Sketch to delete images and rub the trackpad like an eraser to remove text files.
