If you want the photographer to supply you with the RAW images, you are saying to the photographer to NOT FINISH their artistic process. This is why all photographers are reluctant to supply RAW images as you are asking them to supply you with their unfinished work.
The image on the left is unprocessed, straight from the camera. The one on the right has had some basic processing to enhance it. Although the processed image has other problems such as focus, you can clearly see that it looks better. This is where the photographer uses his skills and time to get the best result for the customer.
Several thousand images may be shot at a wedding with today’s modern DSLR camera’s. The photographer has to sort, catalogue and adjust each of the images to get the best and most consistent result for the customer. This work can take several weeks to complete before the images are ready whether they are prints or images supplied on disk.
Supplying RAW unfinished images does not show the photographers best work and provides the customer with a poor result. – Peter