I often run across people using ŝanĝi as though it were intransitive — in a sentence such as la situacio *ŝanĝis rather than la situacio ŝanĝiĝis or li ŝanĝis la situacion. We tend to do this because in English we often (though certainly not always — compare to kill and to die, for instance) tend to use exactly the same forms for transitive and intransitive verbs with related meanings. One does not do this in Esperanto; each verb has a specific meaning, which may be intransitive (it shows what's happening to the subject of the sentence) or transitive (it shows what the subject is doing to the object of the sentence). There are specific suffixes (-ig- and -iĝ-) to change intransitive to transitive and transitive to intransitive, respectively.
There's a potential flaw in the system in English. Take the verb to drown. Consider a man who makes his living drowning unwanted cats, dogs and pet rats. When asked "What do you do for a living?" the obvious answer is "I drown for a living." Obviously, here to drown is transitive; but structurally the sentence is showing it as intransitive. We have to depend on external knowledge to suspect that he's not saying what he sounds like he's saying (you only drown once).
David Jordan, in his book Being Colloquial in Esperanto, lists several verbs that give English speakers trouble in this regard. You can find slightly expanded lists of his on the internet for transitive verbs and intransitive verbs in Esperanto.