[dcb]

Yah, this isn't a conspiracy. If you have a curved top wing it will contribute to lift, but pretty much all airplanes have the wing set at a certain angle of attack so it can "redirect" the air downward also.

I expect the contributions from bernoulli create less drag for the lift they create than changing the direction of the airflow. Hence why commuters use asymmetric airfoils, and I don't recall seeing a sailplane with a symmetrical airfoil (they are especially efficient).

Plenty of airplanes however, (i.e. stunt planes) have symmetrical airfoils and fly well rightside up or upside down. Now the angle of attack still makes a bit of bernoulli effect in reality, but air is being directed downward and newton takes it from there.

Having an airfoil also allows a steeper angle of attack without the flow seperating (stalling). So an airplane with just a curved top wing can nose up with less chance of a stall, a stunt plane can nose up or down and not stall (i.e. if (s)he is upside down and shoves the yoke forward)