Speaking as a professional writer, I think I would have great difficulty arguing to an auditor that the profits listed in my books don't actually count as a "real" profit.

For that matter, the IRS is not going to complain if I pay more taxes than by some obscure technical argument I needed to.

But here's a better analogy than Uber: busking. A busker provides a service to the entire public which may or may not result in a single penny. But busking income is definitely taxable.