TL;DR version - Cobras are a problem, pay a bounty for dead cobras, people start farming cobras to get the bounty. Kill of the bounty and at the end of the exercise you have more cobras than before.
If you do systems analysis, you see this as optimizing the wrong variable. What they wanted were "fewer cobras" but they expressed by asking for "cobra corpses."
The conundrum is identical to the logical fallacy of attempting to prove a negative statement. You can't articulate or measure a 'cobra void' so its hard to reward for it or incentivize it.
In such systems you can either adapt the system to be unaffected by the undesirable trait (hard to do with cobras, there is only so much anti-venom to go around) Or to establish negative incentives around the presence of cobras (say fining people where a cobra is found on their property).
The goal of course is understanding what is the desired state of the system and targeting an input that only amplifies that state and not some other state.
You're right in that in this particular case, the practical difficulties of quantifying "less cobra-ness" or "cobra void" as you call it is difficult, but there are plenty of cases where quantifying the absence of something is straightforward.
The more controversial wording of this is that you can't prove there is no god.
For example: "There are no orange swans" is equivalent to "All swans are either colorless or colored other than orange." Similar techniques can be applied to all statements.
Offer a natural enemy to the cobra..a mongoose..
Skinner: Well, I was wrong; the lizards are a godsend.
Lisa: But isn't that a bit short-sighted? What happens when we're overrun by lizards?
Skinner: No problem. We simply release wave after wave of Chinese needle snakes. They'll wipe out the lizards.
Lisa: But aren't the snakes even worse?
Skinner: Yes, but we're prepared for that. We've lined up a fabulous type of gorilla that thrives on snake meat.
Lisa: But then we're stuck with gorillas!
Skinner: No, that's the beautiful part. When wintertime rolls around, the gorillas simply freeze to death.
"The curious task of economics is to demonstrate to men how little they really know about what they imagine they can design." — Friedrich von Hayek
Eventually the decided to pay per prisoner delivered alive and well, instead of paying in advance. Survival rate increased to over 98%
Makes for a great story/example though! Which I guess is how these anecdotes propagate.
1. They should've reduced the reward over time. If the effort had been successful, there would've been fewer snakes, and less need to get the snake population under control. This makes economic sense event without considering this effect. If there's a million snakes, you really need someone to do something about it. If there's only 10k, who cares?
2. This is why it's important to focus on the actual goal. The goal was not to kill snakes. The goal was to have fewer snakes. Killing snakes was just a means to an end. Actually, the goal wasn't even fewer snakes, it was to reduce the risk of dying from a snake bite. A successful anti-venom would've been just as much a solution as the eradication of the snakes. Of course it's a lot harder to measure, "Are you doing something which is likely to reduce the risk of me dying from a snake bite?" than "Did you kill a snake?"
Otherwise our species track record with introducing foreign species to control a perceived pest has not been particular stellar and usually causes more problems than it solves.
Not spending energy on being poisonous means that a snake can spend it elsewhere; run a bit harder, lay more eggs, lay eggs earlier, whatever.
Venom has a place and a use, but just because you've got venom doesn't mean you're a superior predator. In fact, it seems to me it is most often used simply to allow a delicate animal to hunt prey that can hurt it- not because the prey is fearsome, but because the animal is vulnerable.
Wouldn't this result in locals just breeding more and more and more cobras to cope with the decreasing reward?
That way as the population goes down, snakes become harder to catch, thus more valuable dead than alive. It also makes "farming" a negative pressure, since it decreases the reward per unit.
If you're breeding poisonous snakes to turn in for a reward, and the reward goes away, are you really going to release live poisonous snakes, or are you just going to kill the ones you have and not breed more?
Are there really enough people who keep poisonous snakes as pets for this to happen? I don't think the Florida situation is analogous because of how much less dangerous constrictors are than cobras.
I read the article about Lean Software Development and one of the concept the stuck me is banning local optimization (http://drdobbs.com/184414744).
When this was realized the reward was canceled, but the cobra breeders set the snakes free and the wild cobras consequently multiplied. The apparent solution for the problem made the situation even worse.
A similar incident occurred in Hanoi, under French colonial rule, where a program paying people a bounty for each rat pelt handed in was intended to exterminate rats. Instead, it led to the farming of rats.
If the intention was to decrease the incidents of Cobras/rats causing problems to humans, then isn't Cobra effect a success?
What if they had announced that rewards would stop being offered in a month? That would give cobra farmers a chance to cash out on their supply.
The denominator could also be adjusted based on some biological factors - i.e. how long does it take to breed a cobra, what is the estimated number of cobras out there, so on and so forth.
Further more there could be limits to the number of cobra that any one seller can sell in a the aformentioned period. As well as limit to the total number of cobras purchased in each period - (i.e. - we've bought out enough for now - thanks).
I could go on...
In programming there's always another bug, in economics there's always another unintended consequence or negative externality.