I would consider them Tech companies (now, in 2019), although I see your point. They operate in non-tech industries, but their product is a technological one. Uber is not a taxi company, they are a taxi-calling company (as they would want to you believe), and AirBnB is a short-term-rental-finding company. And their solutions are technical ones.
As software eats into other industries, it will eventually normalize so AirBnB is "actually" a hospitality company, and Uber will be "just" a taxi company (as you suggest) ...since every other company will have products/solutions that are equally technical.
IMO, any bubble bursting will simply be the market adjusting to this normalization.
Uber or AirBnB apps are not some revolutionary tech, they are something CS undergraduate could write, that's why it is inaccurate to put them in the same category as Google (which does some serious ML research) or SpaceX (doing actual rocket science).
Uber's advantage lies in their brand, and early capturing of dominant market share, but their "tech" can be easily replicated.
I'm sorry, but this is a really naive statement. They literally teach Page Rank in basic Linear Algebra classes. Does that mean a CS undergrad can recreate Google?
Operating a service with real-time requirements at scale is a completely different beast than writing a proof-of-concept prototype.
Understanding the concept is a very different thing than inventing it. When Google was built, Page Rank wasn't taught ANYWHERE because nobody thought of modeling web page relevance using a Markov chain yet (well, HITS came pretty close, but you get my point).
These aren’t algorithms, they are just hand waving intuition that is “on the right track” but not quite there. You see similar “prior art” to Newtonian physics, for example, but there is still a huge leap from “oh, there might be something in these linkages” to “if we compute the stationary distribution of the Markov chain over the graph, we know the relative importance of each node.” Kleinberg was the first to algorithmically and rigorously codify this intuition.
My understanding is that Google hasn't relied on Page Rank in a very long time. Depending on who you ask, they use 100-300+ factors to rank pages. Or they switched to an artificial brain that uses its own magic that no one really understands.
I haven't kept up. All I know is Google is useless for all but the most obvious queries now.
PageRank, although deceptively simplistic now (much like the concept of gravity), was much more difficult to invent than to understand. Starting your own Google 20 years ago would have been out of reach of your everyday CS student at the time, even though PageRank is the only thing you would have to “invent” per se (and even though today it is simple enough of a concept to be taught in undergrad).
Today, starting a Google is even harder because of Google’s moat and the advancements such as the deep learning infrastructure used for ranking pages (which still can be replicated if you throw a few Stanford grads at the problem — they don’t even have to be budding Larry Pages in aptitude — but a working replica isn’t nearly enough to compete with Google’s foothold in the market).
It is not even about technology being revolutionary, it's about where they competitive advantage lies. To put it bluntly: SpaceX and likes are technology companies. Uber and AirBnB are "law-bypassing as a service" companies.
