To be fair, SpaceX and Tesla have two sides: manufactoring (low wages) and design/engineering (high wages). Few on HN care about manuf jobs that pay less than 40 USD/hour. When you say "tens of thousands" -- you can say the same about Amazon warehouses. My guess about Tesla: Lean and mean design and engineering teams. Twitter? Bloated as hell with people who don't code or have sales revenue targets.