Airliners also have to work at low speed in thick air, and high speed in thin air. Swept wings, for example, perform poorly at lower speeds.

An airliner has to perform well at both, which is why wings are swept, yet have flaps and slats to modify their aerodynamic profile. Swept wings have other problems, like dutch roll.

Airliners also become uncontrollable above a certain speed, which was a contributing factor to the EA crash (the crew ignored the overspeed warning).