Cory,
Although I agree with everything you said, that is looking from the LFS perspective. And the answer to all your questions is yes, licensed business, reporting taxes, can take credit card and provide receipts, although I wasn't even asked about that nor I was asked to show pictures of the fish, so it's like "well we are not interested".
And on the other hand, looking from the customer perspective we can ask the same number of questions when we do business with a store. Do you quarantine? Do you accept returns? Will you store my credit card number safely or will it be stolen/hacked? And it goes on.
Like you said, you only buy from a handful of breeders, probably because they produce good quality livestock (aside the business requirements). So if I had an LFS and someone approached me asking if I want to buy their fish, I would ask tons of questions and look at their fish and then I'd make a decision. Otherwise if this person actually has great fish and I dismiss the guy immediately, he will become a competitor that may sell better quality livestock than the LFS.
But it's all good. I do this because I am passioned about the hobby and I have dealt with selling livestock that I've bred over the many years including saltwater corals fish seahorses you name it. Feels like it always works out better selling directly to other hobbyists than to stores, until someone can prove me wrong.