The conspiracy theories which have been created to explain it fail to do so. The motivation they ascribe to those making the hard to explain actions are believable, but it is hard to believe that the actions taken would have the desired results.
That poster asked the question, how does a "boutique" vendor compete once they have turned their product into a commodity? They are going to discover they have the same problem which Schick and Gillette have. They both spent a lot of time and money convincing men to buy disposable razors. Then they discovered that it was hard to compete when a razor was something someone bought and threw away after a week or two. They are now spending large amounts of money to convince people to buy their razors with replaceable blades.
I would recommend that you reword your statement to "...were never intentionally stocked..."
The word "stocked" contains within it the connotation of being done intentionally. Since, the general theory about how fish get into a landlocked body of water is that from time to time some fish eggs stick to the legs of waterfowl and rinse off/hatch in a different body of water. I have never heard that referred to as being stocked.
Why do we hear about incidents with drones but not about incidents with RC aircraft?
Because "drone" is the word which the news now uses to describe RC aircraft. The reason they do that is that "drone" sounds much scarier than "RC aircraft".
because you can find the same fish in tiny, isolated ponds that don't show up except on detailed topographical maps. Even the neighbors seem scarcely aware of these ponds, but at some point maybe a hundred years ago the federal government planted fish there.
The problem with your theory is that I know for a fact that those same fish show up in ponds that did not exist a hundred years ago. For that matter I know that those fish show up in ponds that the federal government (nor any other organization) ever planted fish in. The reason I know this is that I know the people who built the ponds and owned the land they were situated on when fish started to appear in them. And yes, some of these ponds now have fish in them, even though no one put them there and there is no way for fish to swim there from elsewhere.