It would be nice if we could all just sit back and be on the first page but here is why the above can sometimes happen
Site age: It's a simple fact, older domains, do have more clout than new ones, more links back and more content. Google works to some extent on a "trust" factor and this has to be earned, older sites are more likelt to have earned this than new ones perhaps set up just to manipulate rankings.
Click through rates. Jargon for how long people spend on your site and the number of pages they visit. If someone searches on Google and goes to a site and bounces straight back the search engine will assume the site was not what the searchwer wanted, if this happens a lot it may conclude the site is not as good as perhaps it thought. However if people engage with your content by visiting different pages, this will be seen as perhaps meriting a higher ranking by being more relevent to the searchers needs.
Links back to the site: Good high quality backlinks from sites of authority with good anchor text, and quality content can have an impact. This may not even be a link the site knows about, or one it instigated, sometimes this is just down to good fortune.
Linked pages: Linking to your own internal pages in a sensible way can have an effect. On 69Design we recently introduced a "breadcrumb" navigation on every page to show a logical hierarchy, the by product is it shows a link to relevant pages on every page. As an example if your mentioning fees on your profile page, show this as a link to the fees page, for agencies perhaps links to related profiles for example.
Competition: It is reasonably easy to rank highly on less competitive terms, so sometimes the worst site in SEO terms can rank number one for something, simply because no one else wants that term.