> What makes Redfin a tech company? Why couldn't prudential (or another brokerage) build the same thing?

They can't because they'd need a brokerage in every state, real estate agents in every metro, and enough leverage to get the data out of the various regional MLS groups.

Its a tech company the same way Airbnb, Lyft, or Uber is a tech company. They have built alot of automation that is difficult to duplicate because you need national workforce buy-in.