@Sylvia B. if you want to finance that property and be on the hook, and your'e left holding the basket, when it turns out that the rehab wasn't done correctly (oh, and by the way the county inspector is wanting to know where your permits and approvals are) that's your option.
The only thing that matters in Real Estate transactions is "can you prove it". An appraisal is an opinion. Comps are only as valuable as the factual basis. Those facts in this case: Are the improvements in place (documentation, pictures, appraisal); Materials cost (receipts and serial #'s), these licensed contractors completed their jobs and have been paid (License numbers, and lien releases). The bank then knows there are no clouds on the title or claims about the product.
If the seller of a rehabbed property did all of the work himself, without permits, without an inkling of building standards, and with the sole motivation of making a profit...would you buy that property just because it looked like other properties? Would you really argue that he should be able to represent his property as being the same quality as one that provided certifications, receipts and appraisals that had factual, documented history. Comps don't mean a thing if they are not based on facts. And that is why you have to document your work and justify your price.
Stan may be a very good rehabber, but you still have to play by the rules.
You said "good for him for making a profit". He doesn't make a profit unless he sells the property. As he moves through this world of REI, he'll sell more properties by playing the game well than by objecting to the rules. If he doesn't like the rules, then like I said: see if you can find a way to make a living off of fear and loathing.