Why does wind usually flow from high air pressure areas to low air pressure areas?



that is how pressure works. Pressure is a measure of force, and the "object" with higher force tends to move the object with lower force. In effect, there is a net force from areas of high pressure to areas of low pressure, and that force causes the air to move. The causes of that pressure differential are a separate discussion, but the idea of force moving matter from one place to another is pretty basic Newtonian physics. The higher the force, the faster the acceleration, so regions with a steep pressure gradient see much more powerful winds.