I mean I think you’ve hit on why this analogy doesn’t work - the photographer’s products are specific to the client, the bakers are not (and have lost value by the end of the day). No baker would bake a bunch of extra cakes for an order just in case the person happened to buy one.
I think if I went to a baker and they made a bunch of cakes for me and then said here are the cakes in your package and I’ll just throw these other ones away if you don’t pay an extra fee for them I would find that a bit weird? And would probably go on r/baking and be like ‘is this normal?’
Yes, that would still be weird tbh. Can you imagine a bakery or indeed pretty much any other business actually saying this to a customer? A baker would not present the other cakes to you as an option.
It happens in photography sometimes for justifiable reasons (particularly if there is extensive retouching required) but it’s not a familiar business model to most people so it’s unsurprising that people aren’t familiar with it and find it a bit gross.