but on the web, there is no street on which to see sites next to each other.
I knew a jewellery company once which had two sites. One was all red and gold and stars and flashing things, the other was all purple and white and curvy things. The items on the purple posh looking one were 15% more expensive. Same products on each - heck, it was the same database, product description and images on each site!
Point is, this is the internet, you can do that kind of thing.
that's the obvious reply, but it fails for two reasons:
1) SERPs are not fixed; they vary from month to month, and even from day to day as new sites and pages appear and are added to the mix. This is akin to the houses on a street changing order frequently, and ruins the analogy
2) SERPs differ between terms - you and I might be adjacent for "cheap widgets" but for "budget widgets" the SERP might look entirely different. This is akin to shops having a million doors, each on different streets, and ruins the analogy.
PPC advertising on said search pages fixes the analogy. As do link directories and, erm, front pages of link sharing sites such as HN (if submitted within the proper timeframe)
I knew a jewellery company once which had two sites. One was all red and gold and stars and flashing things, the other was all purple and white and curvy things. The items on the purple posh looking one were 15% more expensive. Same products on each - heck, it was the same database, product description and images on each site!
Point is, this is the internet, you can do that kind of thing.