What is an edge case

This seems insane to me and will never be properly explained. When you were learning to drive, were you ever told that learning to operate the car is the simple part; the more difficult aspect is understanding the actions of other road users? Thus, might a machine ever assume entire control?
These new automobiles will be semi-autonomous' and capable of travelling up to 25mph while steering, halting, and accelerating in sync with the vehicles ahead. To accomplish enhanced testing, dRISK includes simulated and real-plus-simulated edge cases into semi-randomized, unrealistic training and test cycles. Supposedly, relieving the stress associated with driving in busy traffic. The device makes use of a camera mounted on the front of the automobile that follows the vehicle in front and monitors the road's white lines. Additionally, they will utilize an integrated satellite navigation system to have a better grasp of the roadways. Numerous advanced manufacturers have already produced cars that can drive themselves in certain conditions without human assistance.