Your problem here is not a lack in evolution, it's a lack in your understanding of the word. This system could have been created through evolution - what you fail to see is what evolution is.

Evolution as you're referring to it is the gradual changing of species through natural selection. Those individuals who survive can go on to create a second generation of individuals. These individuals will have attributes more similar to those who survived the previous generation, and will grow up and possibly mate, possibly die (understand that for the purpose of evolution, if you don't mate, you're dead). If we introduce some variable into here, say, a fast predator, those who survive one generation will be those who produce offspring. The offspring will be more like the surviving previous generation, ie, they will be able to run fast. Of this generation, the slower ones will be weeded out and killed, and the faster ones will mate, etc, etc. On the other hand, if the predator is really fast, chances are that the species we are observing here are doomed from the start. None will survive, none will produce offspring, and there will be no evolved response to the predator. If any do survive, they won't survive because they could escape, they would survive because they simply were not affected - the predator now becomes a random event - and there will again be no evolved response to the predator.

In the case of the wasp and the spider you outlined above, all off the affected spiders (read "those killed by the really fast predator") will die. Those who are not stung by the wasp (these are not the fastest, they are the ones who have never seen the wasp) will survive and produce offspring who know nothing of the wasp. What this means is that the only possible evolved response is increased avoidance of the wasp - there's no way there could be an evolved immunity - and since the wasp is probably very hard to avoid, we can assume that the event is random, therefore the spider cannot evolve out of this system.

What I'm less sure about though is how the wasp could have evolved into the system - I can come up with a route along which it could follow, but, like the route between bacteria and groups of cells into specialised cells grown from a single egg, they seem pretty unlikely. Ah well, such is life...