I find this so utterly naive that I am incredulous.
Google is a business. They don't tweek results based in favor of user preferences.
They tweek results based on the amount of revenue they are likely to bring in.
It's not an accident that [in the US] http://www.google.com/search?q=weather provides top links to commercial advertizing driven sites for one's local weather and only portals into the main page of weather.gov rather than the local forecast page.
Google search results aren't the best possible for the most people. They are the worst tolerable for maximizing revenue.
 do employees have to use 20% time for downvoting on HN or is it part of their job?
He complains they're not the same, that if you search from a given location or being in a given demographic you will get different results than other people, and that this fact erodes the trust users have in Google: how do I know if this set of results is the absolute best on a given topic or if Google is simply showing to me what it "thinks" I will like?
It is showing you the most amount of pertinent advertising that it thinks you will tolerate while promoting sites containing similar advertising as high up the page rank as it thinks you will tolerate.
All those links to your G+ friends are promoted to keep you on Google's properties where they can make the most money when you click on an advertising link - think of Google like a DisneyWorld's Magic Kingdom and G+ like Downtown Disney.
This is entirely false, and I wish misinformed people would stop parroting it. There's an extremely rigid firewall between the ad side of the company and the search side. People working on search don't even see metrics on how their changes effect ads, let alone make decisions based on them.
When I want change the way ranking works, there's a big stack of statistics I have to collect. None of them involve ads. All of them involve how useful the results are to a user.
The Weather channel utilizes Google search.
The Weather Underground...well name a Google service they could use and don't.
Accuweather provides plausible deniablity.
On the other hand, weather.gov employs some of the best meteorologists anywhere, provides the official hazardous weather warnings the other sites rely on, and has a wonderfully informative hourly weather graph for any given location.
In other words, Google doesn't provide the most relevant results first when it comes to local weather in the US, it provides the most profitable.
But I'm willing to read your statistical explanation for why this is so. Go ahead and make your case.
Be sure to explain how the special format for the weather page is based on statistical data and not hard coded.
I can't get into detail explaining what goes into our rankings to you. I can tell you that I can bring up a debug view that shows all the signals that enter in to this ranking, and none of them involve "uses google products."
We love for people to complain about queries. That feedback is very useful, and we always need more of it. But when our search results suck, the reason is that our system is too stupid, not that it's perversely smart at funneling you into money making opportunities.
The "weather" page is hand coded - the term triggers a unique piece of code that isn't used for any other search term.
"Pickles" doesn't draw a bunch of icons across the top of the search results and offer short form links to "Mt Olive," "delmonte" and "vlasic." The top link doesn't give me subdomains for MtOlivepickles.com in the way Google search does for weather.com.
When I query "weather," google sends my location to the commercial sites, but not to weather.gov. Explain that with statistics.
 At the risk of further cynicism, I'll explain it with the relationship between WeatherUnderground.com and Google: http://en.wikipedia.org/wiki/Weather_Underground_%28weather_...
Then don't think of it as stupidity then. Think of it as having poor proxies for quality that we have to mash together into a reasonable but imperfect system.
Here's a video that shows how all decisions about ranking changes get made: http://www.youtube.com/watch?v=JtRJXnXgE-A I've been in that room many times over the years, and I have never heard anyone mention or display any statistics that involve ads or revenue.
I think of it as good proxies for revenue. It just makes more business sense, and seems more in line with the fiduciary responsibilities of Google's board in regard to Google's stock holders.
And that's why I don't doubt your statements that the algorithm doesn't do this or that. There are proxies. If Billy Beene could do it a decade ago in Oakland, it is hard to see the smart folks in Mountain View depending on dumb luck to generate revenue from search. And that's the only alternative to tweeking the algorithm to generate revenue.
"q=weather" shows an observable point where hand coding for business interests is accessible and the that holes in the wall are deliberately created. It further shows a correlation between the hole and revenue - note that weatherunderground.com generates revenue outside the ad model.
It's difficult to believe that this practice isn't automated.
Look, I've worked in search at Google for over 5 years. I know all of the signals that determine how results are ranked and most of the details about how they are used. I know all of the metrics that are used to evaluate and tune ranking. I know nearly everyone who works in ranking, and I've seen a decent fraction of the launch decisions and the metrics supporting them.
I'm telling you, with no caveats, that we don't make ranking decisions based on statistics related to revenue. If that doesn't convince you, then I don't know what would.
I think of it as additional information Google supplies, I don't think of it as part of the search results.
I liked the old Google better. Today DDG has the simpler interface and gives me 50% more search results to choose from. Google looks more like the old Yahoo or Netscape portal every day.