In the business world, people typically cite profit/employee or revenue/employee. It's only in SV that people cite valuation/employee..

They're on a run rate of ~$14 billion in 2017 revenue based on their Q1 numbers, so call it $1.2 million per employee in revenue.

I can have a run rate of infinity dollars, if my business model consists of selling $20 bills for $19.

What's their revenue minus costs of revenue?

is that any different from profit?

It is. If they made 20 billion dollars, and then spent 21 billion dollars, and 2 billion of the latter was a big pile of money that they set on fire, it shouldn't count as a cost of revenue.

If, on the other hand, the spent all 21 billion dollars on paying drivers, driver promotions, marketing, flash sales, and coupons... It most certainly should.