Re: Efficient Market
"No it isn't that easy, there's a lot to be said for first mover advantage, market penetration and brand awareness. Google+ was arguably a better featured product (ignoring the various privacy concerns) but it was unlikely to usurp facebook due to the above reasons."
Those factors can have significantly more or less relevance depending on context. For something like a social network, buy-in is all important - if your friends, photos, etc. are all on one network, a newcomer has some serious work to do to convince anyone to switch to it regardless of the quality of the product. Something like a taxi company (and remember, that's all Uber is) doesn't have anything like that. Some people might prefer a particular local company if they know it well, but Uber can't get that, and away from regular locals they have no buy-in at all - people will just go with whatever happens to be convenient.
Pretty much the only barrier to competing with Uber is getting people to set up an account. For an unknown newcomer that might be tricky, but for the likes of Google and Amazon an awful lot of people already have one anyway. Do you really believe people would stick to Uber because of brand awareness and loyalty if they had the option of just saying "Siri, call me an iTaxi"?