Why Inorganic chemistry reaction mechanisms are hard to find?
Reactions can be of order $0, 1 , 2$ or $3$ , but never more. No collision may happen between more than three particules simultaneously. If an equation is written with more than $4$ substances on the lefthand side, it means that the corresponding reaction is a sum of several elementary reactions.
Mechanisms in inorganic reactions are hard to establish because they are made of a lot of successive reactions, in cascade. And each step is so quick that it cannot be studied. For example your oxidation of $\ce{Fe^{2+}}$ ion by $\ce{KClO3}$ is probably a series of at least $6$ steps which are all nearly instantaneous : To be able to study such a mechanism, the $6$ intermediate states must be observed for at least some nanoseconds. If the intermediate states are too short living, all we can do then is to make hypothesis without experimental arguments.