For anyone who might read this and jump to conclusions, building inspectors and home inspectors are very different things. First and foremost, allow me to say this: home inspectors are not universally stupid and building inspectors are not universally geniuses. There are some very smart (and stupid) people in both professions. The education requirements are not really so different as this comment makes it sound, but building inspectors have more rigid requirements for certifications at the outset, because their profession is one of understanding the latest codes, which is a very rigid and defined expertise. This is a problem in home inspection, because it effectively makes it easier to become a stupid home inspector than it is to become a stupid building inspector (but I assure you, both creatures exist).
Without regard to this, the professions differ altogether. You might find yourself wondering - why are building inspectors not home inspectors and vice versa? Because the professions do not overlap like you might think.
Building inspectors inspect a building when it is being constructed to make sure that it is up to code. They inspect the building in stages, while everything is exposed and easily visible. Home inspectors inspect a building after it has already been built (often several decades after it was built) to try and determine what current conditions are and how the building has withstood the test of time. Sometimes this involves things that are also violations of code (either at the time of building or currently), but often it involves intuition and knowledge and experience of how things are or could be going wrong, without regard to code requirements. Building inspectors do not generally meet the person who will be buying the building they are inspecting. They deal with the people who are building it. A building inspector never had to deal with someone calling them back and saying "you told me this was OK."
Because home inspectors have to deal with every type of expert in every field potentially telling a home buyer that the home inspector was wrong (or worse, an idiot), home inspectors are often more critical than necessary. Good home inspectors are hard to find, but most home inspectors are at least decent (most jurisdictions these days have education and licensing requirements and the really bad ones don't last for long) and all of them that have been in the game for a while are always trying to improve their knowledge, their skill and their usefulness. How long a home inspector has been in business is, in my opinion, a good indication of how good an inspector he/she is.
Just thought I'd put in my .02 (yes, I am a home inspector - 10 years now).