That's part of it. The other part of it is that digital advertising business models turn out to be close to zero cost. There's very little "product cost" when you amortize tech cost over billions of ad impressions - the "cost" really comes from "reduction in addressable market" - ie. what portion of the audience will stop watching the platform due to ads. At least for Google and Facebook, the answer seems to be negligible proportion and in China at least, publishers are finding that many of such people are willing to pay for an ad free experience if you have killer content.

Taxi service is a much more constrained business - you have to pay out product cost plus some incentive to generate supply but you have a strict price ceiling on scaled demand and a lot of competition. The answer for the previous generation of entrepreneurs in this space was to execute regulatory capture and institute a system of restricted supply to boost prices (ie. Medallions, permits etc). So it's going to be interesting to see how these businesses evolve.