This isn't even close to accurate. It is true that they are not required to be certified, but like any other business owner who wants to grow a business and get more clients and less law suites, there are some VERY good inspectors out there.
You will get what you pay for. A good inspection/inspector will have a infrared water leak camera to test behind the walls. You probably don't need a radon test or meth test.. I have had both good and bad inspectors.. and found one that I absolutely LOVED.. but I lost his info, sorry
A contractor isn't going to be a good option. They higher people to build things.. they do not check in the wall leaks, under ground pipes, etc.