Everybody and their cousin's cat will tell you they know how search engine optimization works. This knowledge is largely derived from what they've heard or read online. And legitimately, I've become and overnight "Expert" in several fields via YouTube and a crazy Russian tutorial too, lol. But that doesn't mean I can actually make a living at whatever instant skill I just learned. There's a world of knowledge and experience missing with that kind of shotgun education. And that's what's missing with most people I see claiming to "know SEO". They know the theory and catch phrases but they don't actually compete online. They can't show results directly related to their efforts.
Claims of SEO Expertise aren't limited to instant amateurs either. I personally know SEO Consultants at Internet Ad Agencies that have made a lot of money talking about or selling SEO services on a very high level, who have never done a single implementation. You know, the work that actually moves a keyword ranking. Point being, they don't really know how Google finds your website someone else does the actual SEO optimizations, a specialist somewhere in their organization does the heavy lifting for them. That's the person that knows how Google gets there and why. I know this because that was my role in a few SEO Companies and Internet Marketing Ad Agencies....and you'd be surprised how many of those big ad agencies with big fees are really outsourcing their SEO work overseas and have no idea what is being done with your account. True life.
Anyway, this isn't anything new or earth shattering, most businesses are structured the same way. People that "know SEO" are like talking to the salesman as opposed to the "SEO Specialist" or mechanic that actually fixes your website. A specialist is the SEO guru geek guy (that's so me!...the geek part) with the expertise to make judgement about what should be done and how to execute those changes effectively and why they work with the rest of the marketing strategy. A truly experienced SEO Specialist will SHOW YOU top rankings and be able to explain why they've been successful over the years.