Many of us have jobs that are somewhat based on some law/regulation mandating something. So someone has to fill that need, whether it is QC in a manufacturing plant, processing/approving human medical research studies (which my Wife does for a hospital conglomerate) that meet FDA requirements or a gun dealer processing a transaction.
I got into shooting in the mid-1970s and the laws wrt interstate transfer of guns was firmly entrenched (actually much worse than today) with FFLs being required. I've never researched the back-story on when this all took place (might have been with GCA 1968 after all the assassinations or perhaps even earlier, don't know).
Many dealers indeed make significant money due to this. On the other hand there are some dealers who will refuse to do interstate transactions either due to greed (buy it from me) or ignorance (tons of that in every gun shop) . . . no excuse for this as BATFE sends every FFL a book on all states/cities gun laws that impact sales (only, doesn't cover other aspects of gun ownership). I'll bet not 1 in 10 dealers ever opens up the book at all (or runs the CD).
Realizing in Free America a DL is all the ID you need for a FTF in-state transaction and that is NO PROOF at all that the person isn't a PP, I don't understand the logic of someone being trusted merely since they reside in the same state vs. someone in a different state. A partial resolve that could be a reasonable compromise (IMNSHO) should be showing a valid LTC/CCW from any state to prove non-PP status for FTF between residents of different states, but I never expect to see this happen. Hell we can't get handgun transfers from an FFL in a different state made legal! Now that everything is computerized a NICS check in your state or in another state will have the same exact results, so there is no public safety issues really.
And the bolded part you wrote is what got me on this topic to begin with. I bought the bolt action rifle from a guy I've known for years and went to war with (seriously).........but that state line between our houses only a few miles apart forced me to go to a gun shop to have him sell me that rifle "legally". But two complete strangers that have never met can make that same transaction if their drivers license happens to have the same state on them. Guess I should just let it go.......I'm thinking too much to try to understand Fed reg from the ATF.