If there was away to police this where the artist would get royalties on every print sold, this would work. However, there would be little if any quality control. Some 3d printer item sellers just want to make a quick buck, by outputting the roughest and unprocessed print around.
For example, let's say a painter, paints a lovely landscape painting. Several sellers who have a scanner come around and offer the painter a royalty for every print they sell. Some sellers use poor inks and printers, and scanners that don't have a colour gamut that picks up the proper hues. Some customers are not satisfied with the reproduction, and won't buy any more prints, thinking the artist is to blame for the poor quality.
In the real world, the artist would go to a professional print shop that specializes in replicating paintings and arrange for artists proofs, along with a set number of prints.
In your world, it would be like the wild west, with no quality control, and dubious accounting.
You can always contact an artist and arrange a special contract for you to print out their work. I'm not certain how they would ensure that you would be honest in ensuring that all royalties would be paid, though. You could arrange a higher price to be set for buying the model outright where you would be able to print the models without any royalties.