If you think proponents of the "free market" think it's simple, you don't understand them. Or it. It's precisely because it's so complex that managing it is prone to error.

I don't actually understand why the same people (in general) will assert ecologies are extremely complex and we shouldn't meddle without being very careful to understand the effects, and at the same time think that the market is manageable from the top down without unintended consequences on the same order as the intended ones.

That's a view I can certainly buy, that intervention must be careful and is error-prone--- perhaps even so error-prone that it's rarely worth doing. In libertarian circles at least, though, I often encounter a much stronger claim. I don't hear people say things like: maybe it'd be great if we could intervene in an ideal world, but alas such interventions are error-prone so we'd better not. Instead, a much stronger claim that no intervention is necessary because the unfettered free market is already at least reasonably close to ideal. This is particularly strong in Rand-influenced areas of the libertarian universe. The explanations are usually some extremely simple version of classical economics, invisible-hand, etc., leading to assertions that the free market efficiently allocates resources, rewards merit, etc.

That's the part that reminds me most of the ecologists: a belief that we're fortunate enough to live in a universe perfectly constructed such that these complex dynamical systems (economies, ecologies), if only we'd stop mucking with them, would live on in magical harmony, aligning with normative notions like "merit" and "balance" and whatnot. I tend to view them both, instead, as difficult to analyze, hugely complex systems filled with all sorts of weird attractors and unstable states, which won't necessarily result in particularly great outcomes whether left alone or not.

In short, I agree that most of the people who claim to know what will happen if you intervene in a market are naive (i.e. unintended consequences are likely), but I also think most of the people who claim to know what will happen in a free market (e.g. that it will reward merit) are also naive. And most libertarians I've met fall into the latter category.