This is a really interesting blog article explaining (without too much detail) the way google filters similar pages from large corporate websites to prevent an appearance of duplication.
Google ONLY displays the highest ranked pages. I would imagine this particularly applies to brands that offer services regionally and have a number of similar pages on their site. Unsurprisingly, the remedy is to fill each page with unique content/links etc. The question is: are the Big Brands aware of this?
Whichever pages have the highest ranking power and are the most relevant are the ones that end up showing first and avoid the filter