Technology makes it easy to edit a single photo, turning it from color to black-and-white to sepia, removing red-eye, cropping. But when 3,000 photos need to be edited, that's going to take some time.
Yes, it's quite easy for a photographer to upload photos to a DVD or to a digital file you'll access, but it's the time and focus on assessing each photo, seeing good but wanting great for you, fine-tuning, painstaking work. Plus, the emotional value of the photos taken, as moments in time on this one momentous day, that add up to the cost of this service.
Plus, another one of those details you might not know about from inside the photography industry: equipment needs so be updated very often to keep current and offer you the best quality of photos and editing possible, and this profession maintains a high amount of expense in their online functionality and online security areas. The company's studio will create some overhead expenses for them, which factor into their prices, and this is a service (taking photos) plus a service (editing photos) plus a service (creating photo slideshows and collections,) rather than a single-level service like making cupcakes. So, with so many layers to the job, fees are naturally higher.