It never ceases to amaze me how many supposedly educated, intelligent professionals who presumably once attended some sort of school and are able to hold down a well-paid job and navigate the average room without bumping into the furniture cannot manage to spell the word "its". It is, after all, a word of one syllable. It's spelled exactly as it's spoken. It's clearly related to "his", which nobody but the criminally insane would write as "hi's".
The problem is that in English, as in other languages, we are able to run some common word combinations together for convienience, brevity and fun. In French, for example, "ce est" ("it is") is usually abbreviated to "c'est", which, conveniently for an everyday word, isn't easily confused with anything else. In English, however, shortening "it is" or "it has", leads disastrously to "it's", resulting in a tragic situation in which two different things sound the same.
The situation worsens once we consider possessives. "The cat's whiskers", for example, indicates the whiskers belonging to or otherwise closely associated with the cat. By a convenient convention, if we are referring to many cats we shorten "cats's home" to "cats' home".
Now consider the impact of a sentence such as "It's a great car but its handling's let down by its suspension" on the average magazine journalist or IT manager with a limited capacity for philosophical introspection. He or she will have to keep in mind both the it is = it's construction and the my/his/hers/ours/whose one. At the same time. Uh oh.