>I wonder if it's simply a matter of engineer/development headcount
That may be one way to look help define it.
However, in Redfin's case, it's simpler than that.
The 3 founders[1] are David Eraker (software programmer), Michael Dougherty (electrical engineering & programming maps), and David Selinger (ex Amazon data mining).
Since the founders are still active and dictate the company's "DNA"... it looks like a tech company to me.
Similar to Jeff Bezos (computer science with some programming before D.E. Shaw) starting a tech web company that happened to sell books instead of thinking of him as a bookseller that wanted to be online.
That may be one way to look help define it.
However, in Redfin's case, it's simpler than that. The 3 founders[1] are David Eraker (software programmer), Michael Dougherty (electrical engineering & programming maps), and David Selinger (ex Amazon data mining).
Since the founders are still active and dictate the company's "DNA"... it looks like a tech company to me.
Similar to Jeff Bezos (computer science with some programming before D.E. Shaw) starting a tech web company that happened to sell books instead of thinking of him as a bookseller that wanted to be online.
[1] https://en.wikipedia.org/wiki/Redfin#History