I agree with you. This is why I will probably never go contracting. These my observations:
You have to be an expert in the required area. Example: you have to be a Java Developer. If you are a software engineer that uses Java as one of your tools, it's not gonna fly, because god forbid you won't know by heart some java specific library/method/quirk/etc during your interview - this will be immediately filed under as a "NO" under "can hit the ground running" section, no matter how good you are at software engineering as a whole. In the end you will work with handful of "proven" (read "old, outdated") tools and become an expert of handling all kinds of legacy mess.
You can't know everything and don't need to know everything.
What I offer is a lot of knowledge for the core items I currently use (Dynamics CRM, C#, Javascript, SQL) and a very broad set of knowledge based on 20 years of been there done that seen what happens if you do it that way...
The requirement of any contractor (or consultant) is to convey a sense of competency / trustworthiness that allows the interviewer to believe you either fit the exact requirements or provide enough additional value (in my case 20 odd years of battle wounds and stories of utter disasters) that you are the person who will add the most value....
It's not necessarily true, I was interviewed as a permi but chose to join as a contractor instead. From what i observed the ability of contract developer is not necessarily better than a permanent.
You have to be an expert in the required area. Example: you have to be a Java Developer. If you are a software engineer that uses Java as one of your tools, it's not gonna fly, because god forbid you won't know by heart some java specific library/method/quirk/etc during your interview - this will be immediately filed under as a "NO" under "can hit the ground running" section, no matter how good you are at software engineering as a whole. In the end you will work with handful of "proven" (read "old, outdated") tools and become an expert of handling all kinds of legacy mess.