Why It’s So Hard to Make a Reliable Self-Driving Car

Two decades ago, the US military kicked off the race to build self-driving cars by sending a fleet of fledgling robot vehicles across the Mojave Desert in its seminal Darpa challenge. By 2015, autonomous vehicle technology was being widely pursued, and the industry was abuzz with predictions that driverless cars would soon be everywhere.

It didn’t happen. Some legacy carmakers and startups abandoned their efforts, citing excessive costs and complexity. Regulators stepped up scrutiny of the emerging technology after crashes involving cars equipped with partial-automation systems.