interesting reading your take on it.
i can't comment on anything Google related here i'm afraid but i'll share my other thoughts.
you comment at one point about the reliability of geographic data.
this is in fact one of the easiest pieces of information to gather.
source IP addresses are allocated by country so it is possible to tell fairly easily where the request has originated.
the exception to this is often China where technically proficient users often use a proxy outside China to evade the Great Fire Wall.
towards the end you speculate about the size of the robotics market. i think you are underestimating the value of the non English speaking markets.
Germany for example is full of electronics geeks.
there are lots of electronics websites in German including a fair few robotics ones.
any users searching in German will only rarely hit your English language site.
i know some Dutch and German guys who are into homebrew electronics of one description or another. i would imagine there are at least as many robot geeks in each of those countries as in the UK.
the same could be said for French, Spanish, etc.
now for a bit of extrapolating...
your statistics from India are expected. huge well educated population who will be entering search results in English.
you are probably only getting a tiny percentage of the share from the rest of Asia though.
think about Japan... huge economy. technologically advanced.
lots of robot geeks there = lots of web pages.
only rarely will you ever land on one as the result of a search as you are searching in English when the sites are in Japanese.
the same as Japanese people will rarely land on your site.
the same could be said for Korea, China, Taiwan, etc...
the Asia-Pac region has a huge number of internet users, very few of them using English.http://www.ipligence.com/worldmap/
it is curious you get lots of Thai and Indonesian visitors on your site...
i'm out of ideas there.