Well, yes if you would like to get technical about it. It would cost more than that. But if they are just putting the dog down and it spending a total of not more than a half hour in the facility...I don't think that the cost of rent and utilities and equipment and etc can come into play. Even for a surgery and an overnight stay would add to that much in cost of all the extras other than supplies.
But it's not a technicality. It's a cost of business. It's a cost that needs to be included in every procedure, including euthanasia's, or else the vet may not be able to pay their next set of bills. So even for a half hour spent euthanising the animal and letting the clients grieve, the sunk costs, opportunity costs, and associated costs (bills) involved in that
have to be accounted for because it's a business first and foremost and can't run if they just disregard those costs.
And again, the vet could have stabilized the animal with a shot of a pain killer while the animal was transported to another vet, yet the owners didn't elect to do that. Also, maybe there was some other reason for them refusing the euthanasia that the vet didn't disclose? Or the story teller didn't disclose to make it more sensational? One day we had to cancel and move all our surgeries onto other vets in the area for the day because a technician dropped the bottle of Isofluorane (a $200 bottle at that) and it shattered on the floor and our replacement bottle (which was already on order) wasn't due to arrive until the next day.
It may not be a devil vet refusing to euthanize the animal because they're morally demonic like people in the thread would like to believe. Instead, perhaps he simply couldn't do it because the anesthetic he uses to OD the animal wasn't available, he was out of it, or some other viable reason.