Again it depends, as long as she isn’t tracing from the show or claiming these are her characters, if she’s putting a spin or adding her own original take to these works (eg using their own art style, making a fan comic, taking suggestions and drawing them, an AU etc) its fine, also she’s also somewhat right, in the context that large companies don’t give a sht and the people who work at these companies are often paid quite bad and don’t care either, I completely agree that its rude to not ask for permission if its a smaller creator though and a company/ corporation consits of several people who may be affected; I’d understand not selling art of a character like Mickey because he’s copyrighted and protected property of disney, making fan art of a *copyrighted or trademarked character and mass selling it for profit is wrong (in most cases), but if someone wants to pay an artist to draw their favourite characters interacting then why not? Also many artists purchase licenses that allow them to make and resale art :D I looked through some articles on this topic a while back and most of the issue was surrounding legal steps with copyright, in summary if its not a carbon copy and the character is open for use, you can sell art, the only problem should be when someone is tracing from a show and selling it or using a highly copyrighted character like Elsa or Mickey and not purchasing a license