Rojo, it's not about testing individual shoes. It's that nobody has any concept of what an "unfair advantage" even means in the context of footwear. If actual scientists can come up with a definition of "unfair advantage" and then propose criteria for testing footwear against that definition, then the IAAF might be able to do something.
That's why your analogy to drug testing doesn't work. It's not like the IAAF is saying that there is such a thing as an illegal shoe that the IAAF is capable of identifying. If that were the case, it would be totally fair to complain about leaving it up to third parties to turn in the cheaters. But that's not what they're saying. They do not know what an "unfair" shoe is, and neither does anybody else.
So basically the IAAF's shoe rule is comparable to WADA's three principles for banning a substance: You're not breaking the rules for taking a substance that violates those principles, but WADA uses those principles to make more specific rules that athletes do have to follow.
I'll grant that the IAAF probably should not have codified the shoe rule as a rule, which implies that it's enforceable. That's what's causing confusion and getting people worked up. Really, the IAAF should have just released a statement saying that they're concerned about the issue, that they're looking into it, that they welcome comment, and that they will take action as necessary. The reason that the shoe rule ended up as a rule is most likely that it was replacing an existing shoe rule (the "spring" rule of Spira infamy) that was even more problematic.