Why Uber doesn't just send the nearest car

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Uber doesn't just send you the nearest car. Because the nearest car can be the wrong one. Here's why.

The closest car in a straight line? It might be across a river. Or up a one-way street. Distance isn't time. So rank by ETA. How long until that car reaches you. ETAs cost real work. So score only up to 50 candidates.

Here's the score. ETA carries the most weight. 0 point 4. Then rating, and acceptance rate. 0 point 2 each. And how long the driver has waited. Fairness is in the formula.

But here's the catch. Rush hour. Requests land back to back. Pick the best car for each, one at a time? It backfires.

Rider one grabs the nearest car. Rider two is left with a far one. So collect 2 seconds of requests. Solve them together. Total pickup time drops. Each driver still gets one offer.

Two seconds of waiting buys a better match for everyone. Nearest isn't best. Rank by time, not distance.

Full breakdown in the lecture.