I interviewed at a ride-share company (one that was not then working on self-driving cars mind you) once some 5 years ago or so and was shocked to find out that

I interviewed at a ride-share company (one that was not then working on self-driving cars mind you) once some 5 years ago or so and was shocked to find out that they had 1,000 software engineers. What did they need so many engineers for?! But then all their queries were hand-written to some key/value store w/o a query engine -- that has to explode your engineering needs a bit, though maybe still not to 1,000.