Most developers work at banks, insurance companies and other “enterprise” jobs. Even most developers at BigTech and who are working “at scale” are building on top of scalable infrastructure and aren’t worrying about reversing a btree on a whiteboard.
Agree that the whiteboard thing is often not applicable but it's so nice when a developer has efficient code if only because it indicates that they know what's going on and also that there are fewer bugs and other bottlenecks in the system.