It's not even about the aerodynamics, it's about basic phisics and relative motion. There's special phase of flight where airspeed changes with turning up/downwind and it's called taxiing. As soon as your wings take over from wheels, you move through the air and together with it - airspeed will stay the same but groundspeed will vary. It's counterintuitive for ground dwelling mammals but your inertia is now relative to airmass, not to ground.