250k may well be an average, but not the type of average that matters. The few high-pay people warp the average. They will not be culled before an IPO as doing so will reduce confidence. Uber needs to keep its headliners. They can only cut from the plebs costing in the 50-100K range. So either they need to fire 4x as many people, or a cull won't solve the problem.
I doubt that there's a single full-time employee (in the US) that only costs them 50k/year. Total overhead costs are a lot higher than the employee's salary. I have no idea what the distribution of salaries look like, so this doesn't necessarily invalidate your point.
Their sales/brand reps are reportedly paid 20$/hour, which works out to about 40k. I don't know what the benefit package is but I doubt it's much, as I doubt they are all paid for full 40-hour weeks. So I assume they have a pool of sub-40k people.
