You've got a document and routine that's gotta be absolutely perfect. The document and related "book(s)" are subject to audit. And you've got to maintain this document for 20 years.
That's a fairly hefty burden.
I'm Chief Inspector for a FAA repair station that among other things, refills oxygen bottles for the airlines. The actual time to refill the bottle is maybe 10 minutes. Behind that, you have the nearly 200 page quality manual your shop has to abide by. The customer requirements we have to abide by. The process of checking it in. The Final Inspection. And the Federal requirements for shipping hazardous materials. The FAA and DOT hazardous materials paperwork we have to maintain a minimum of 2 to 3 years that is also subject to audit by the government. All for $35.
I feel the pain of a FFL. $10 ain't worth it.
There's also the risk of those bottle exploding during filling - Which can disassemble a human - We had a 17yo lose both arms here on LI some years back. I saw a bottle get dropped and become a missile, ricocheted around the shop, then went through a block wall, then another, then through a car.
Transferring a firearm isn't near as risky.
Now, I really think the plan behind that $10 was so that the Law-Abiding-Citizens would say "Oh, that's 'reasonable' " and not protest it, so it could pass. - and ... AND so that FFL's WOULD says "No way, can't do it" and NOT do private transfers...
I kinda think we might have been better off if all FFLs together said NO - then the people would get off their butts in force.
Suggestion for one of our FFL's - how about a video, show us the procedure and time involved... Maybe that would stop the whining.