Big planes fly better...

You are forgetting one very impotant thing. Inertia!
A heavier plane must be hit by a stronger turbulance, or the same turbulance for a longer duration to be affected. The airfoils may not care about air speed, and the size of the air molecules may not matter, but shear mass does...

Put a marble and a bowling ball on the kitchen table and try to blow them both off...
Same aerodynamics, different mass..


Just my semi-educated guess.