This article, showing the countries that the doodle appeared in, also aroused my curiosity.
India, obviously, because that is where he lived and was active politically. The UK and, by extension, Ireland also make sense because of the former colonial connection. I don't know why the other countries were chosen. Who decides these things?
There is also one glaring omission. Google is not bringing Dr Ambedkar to the attention of Americans. Perhaps they don't feel that remembering an activist who campaigned against caste discrimination in a country on the other side of the world is relevant to them? Despite the fact that he did in fact study in the US. But it's ignorance of people like Dr Ambedkar and the injustices he campaigned against that perpetuate the myth amongst certain SJWs[*] that only white people practise discrimination and the only people who suffer from discrimination are non-white. OK, when we remember Dr Ambedkar and his work, the people suffering were non-white, but they were being oppressed by fellow Indians, not by white colonialists.
On both my visits to America, I was struck by how there was absolutely no news about anywhere else in the world (unless it was an area where America was currently engaged militarily), whereas here in Europe, we seem to be swamped by news about America. It's no wonder that so many Americans are so ignorant of the world beyond their borders. This would be fine -- if sad! -- but when it comes to the internet and SF fandom, Americans do interact with citizens from everywhere and it is becoming increasingly tiresome that they persist in believing that everywhere is just like the USA and that when people try to tell them otherwise, for example should someone point out that in the UK the most discriminated against people are probably Roma travellers (who are white) and that the ones that cause people like UKIP to get their knickers in a twist are from Eastern Europe (and white), they seem to genuinely believe that this is not possible and that only non-whites can be suffering. Trying to tell them that, it's All Much More Complicated gets nowhere because they are so convinced they are right and black/white thinking (both literal and metaphorical) is so ingrained in their psyche.
[*] Social Justice Warriors, the name given to people who campaign single-mindedly and stridently about oppression, mostly that of non-whites by whites but also other forms of oppression sometimes get a look in. Despite it being a good and noble thing to try to stop oppression and make the world a better place, ignorance and even wilful blindness means that they often make enemies of people who would be totally on their side if they didn't try to make a false dichotomy of white people evil/POC good.