Lol, none of this matters, this literally doesn't happen, unless there's a bunch of corpses related to the gun purchase, at the same time, somehow. Stop making shit up that doesn't exist, for the love of god.
Denials get guns taken from them by the feds all the time and it rarely ends up being newsworthy. Hell the ATF doesnt even arrest most of these
people absent some other issue or a pile of felonies they can get on them. Even if someone was arrested, it's unlikely to be noticed unless there are corpses involved.
Yes, a few do as a risk aversion strategy WRT civil suits, etc. That's literally it, the entire reason is because of perceived civil liability. It's cheaper for (box store here) to lose
the sale or even the whole customer than it is to deal with the problem if the 1 in 10,000 odds hits true and they get sued somehow for it. The idea being that if they got sued, even if
it was dismissed out of the gate, is going to cost htem shitloads of money. With the small margins sin the business, It's cheaper for them to fire like a dozen customers than it is to pay for an attorney's retainer for that incident. Especially for a box store which, at any random moment can fire a dozen or two customers and nobody cares.
There's also a few minor, circuitous, workflow based, paperwork violation traps that can come up in an ATF audit, that are avoided by dealers by not doing default proceeds, but this is the height of laziness, frankly. I'm not even going to go there because its dumb.
Lol no FFL I know of that likes staying in business will give full $ back on a used gun. MAYBE if it was genuinely unused, with ZERO signs of firing, etc. Or MAYBE if the customer
in question is normally otherwise a big spender in the shop. Of course you're going to cut that guy a break, because he's churning revenue when hes around.
However, it still remains that.... not proceeding by default on the small odds it turns into a deny, because "it might produce this scenario of a customer being dissatisfied about a refund" is straight up mental retardation grade logic.
That's going further into "angels dancing on the head of a pin" territory.