Hobbiests perpetuating misinformation, falsehoods and marketing slogans as technical facts about camera functions or techniques.
It drives me insane, the amount of high profile IG and YT personalities prattling on with nonsense like longer focal lengths cause compression, or high ISO causes noise, or lenses are only sharp at f8.
It has been clearly established by scientific research, that people born since 1993 (i.e. people born to parents who became adolescents after the internet became ubiquitous), trust information on the internet more than they do books, technical manuals, or in-person experts.
The majority of people on this group not only trust the internet more by default, even the sketchiest of sources, but they weigh the value, and factual reliability of the information, based on the popularity of the individual sharing it.
A physics professor sharing an established fact about gravity, with no online presence, is less likely to be believed than a teenage college student with 20,000 followers on whatever social platform, telling you gravity is fake.
We have a moral and ethical responsibility to ensure that all information we share on the internet, especially those with large followings, is correct. Even the ones who try to disclaim their words as opinions and tell people they are not experts will still be believed over experts, the science proves it. Its not enough to disclaim credibility.
The short and blunt answer: you are wrong.
You say your wife is an artist so you understand the value of her experience and equipment all had to be considered in pricing her work. Well let's assume shes a painter and she is commissioned to do a painting for someone. She is paid a fixed fee for 1 finished painting. She goes through 3 canvases trying different approaches to the commission before she presented the finished piece to the client. They then insist that they are entitled to all of the other canvases too and act outraged when your wife insists that they would have to pay for her to finish them if they wanted them. Sound reasonable?
This photographer was paid $1800 for make-up and wardrobe, 2 hours of studio time with a skilled professional, post processing time to "finish" the images and 15 finished images. The images taken in the studio don't belong to you. The 15 you paid for belong to you (with certain rights retained by the photographer). It's standard practice to be given a proof sheet of low res watermarked images for you to choose your preferred images (personally I wouldn't provide 300, thats choice paralysis territory for a lot of people, but I digress). If you want more, that's got to be paid for. That's stock off the photographers shelf and further time and effort to finish the additional images.
No self-employed photographer who wants to stay in business will ever give or sell unfinished images to anyone. Asking for unfinished images is like getting your bathroom remodelled but asking the contractor not to fit any faucets or fixings. You'll have to do that yourself or get somebody else to finish it and the work likely won't be up to that contractors standard. If anybody else saw the finished bathroom, they will likely conclude that the whole of the remodel was done by the contractor, including the shoddy finishing, and their reputation and business will be negatively impacted as a result.
In short, you get what you pay for. If you want more, you pay for it.