In my last attempt to convey something..... I will just restate the example that another posted earlier.
Think of riding on a buss. Does it take more energy to sprint to the front, stop, turn 180 and sprint back the other direction down the aisle if the buss is traveling at 100mph vs standing still in a parking lot?....
Or fly a rc helicopter in the bus. Does it fly and turn differently if the buss is moving down the road at a constant velocity (same as traveling in the wind), vs flying the rc helo while the buss is parked?..
Wind does NOT exist while flying. It can only be observed in reference to the ground. (again this is assuming no gradient, gusts, or sheer) Just as we are not effected by the fact that the earth is rotating at over 1000mph, and it is traveling in orbit around the sun at 18.5 miles per second (or 66,600mph), and the universe expanding at between 55 and 85km/s/Mpc depending on who you believe!!
Boy if we had to account for these, in addition to upwind and downwind when we turn.....flying would be even more difficult.