When I shot film this is exactly what they would get is an album full of 4x5 prints (I was shooting 6x7 format) and it served two purposes. The most obvious was for them to choose which images they wanted to have in their personal, parent, etc. albums. They could purchase the proof book for an additional charge.
In the digital age I put everything online for them to choose from. I do have an option for them to have a proof book made for them, again at an additional charge which I waive if they order a certain amount of reprints. The images in this are all watermarked to prevent scanning and they are not all perfectly color balanced and sharpened to its optimum levels. The customer is told this. I have only had two customers in the last 18 months actually ask for this option. The online images are resized to fit most monitors and are also watermarked to prevent unauthorized copying and the customer is told that all ordered prints receive final editing.
When you look at the workflow, I put approx 350-400 images for a full day wedding, pretty close to what I did in the film days. Out of those, how many are they really going to order from, not that many. I don't have the time to edit them to what I would call the final product. I have a set of TIFFS (in most cases but do shoot some weddings in JPG) and then I have several different actions that I will run through the Image Processor to come up with the final set that are either printed or put online.