Oh, so when Old Joe triples the price of a brick of .22's he bought at WalMart to supplement his S/S check and sells it at the local flea market or gun show its all OK.
Now I get it, OK for the little cheat who likely doesn't have a tax license, but bad for the B/M store, who is following all the rules and laws.
The obvious answer to your question is "yes", it's all good for Old Joe to do this because we see it happening all around without a huge public and political backlash.
About the ONLY time there is a huge public and political backlash against similar practices is during certain times of civil emergencies, such as when some coastal region gets slammed with a hurricane or something. Then the public and local government comes down on these people like a ton of bricks in a most vindictive fashion.
As for a "tax license"...a tax license isn't what you're thinking about. And even if it were, a business tax fee is based on projected gross income based on previous income periods. Less than $10,000 gross is typically no tax fee. Between $10,001 and $50,000 may be $30, and so forth. Old Joe would have to buy and sell 400 bricks a year at a 100% markup (assuming $25 a brick) in order to make $10,000 profit. Frankly, I don't see Old Joe getting that much ammo a year from the retailers.
http://taxes.arlingtonva.us/business/business-license-tax/
If people are selling things for a profit, yes, they are supposed to pay taxes on the profits. However, Uncle Sam historically hasn't pursued small time infringements on this because it's cost prohibitive for them to do so. Doesn't make it right, I know, but that it also the way it is.
And even if they DO pay taxes on it, there are ways to mitigate a significant portion of those, even for small timers. They can, for instance, deduct business expenses. By the time Old Joe finishes doing this with his part-time ammo flipping, he may very well end up not having to pay taxes anyway.
Personally, I don't care what Old Joe does. He's not likely to be selling his overpriced .22 LR ammo like hot cakes anyway...certainly I haven't seen .22 LR flying off the tables at the many gun shows I've attended in the last two years. Old Joe's prices are high enough to keep that from happening...which means if anybody really NEEDS it, Old Joe's gonna have some for him. Good on Old Joe.
And who am I to judge all these other people flipping ammo? They ain't making a fortune doing it because they have to get their supplies from the various retailers, just like all the rest of us do. Which means they only get a trickle of .22 LR to flip. Maybe flipping a couple bricks or so of .22 LR each month helps pay for diapers and formula. Maybe it's helping pay the mortgage or rent. Who cares? Social Security isn't paying people like Old Joe much to live on, anyway, so more power to them.