Why do Boeing planes have more flap settings than Airbus planes? The Boeing 737 and Airbus A320 are similar in size and performance. They are direct competitors. Boeing seems to have eight flap settings (1, 2, 5, 10, 15, 25, 30, 40) whereas Airbus seems to have four flap settings (1, 2, 3, Full).

What is the reason for Boeing having twice the number of flap settings? I believe it is similar on other models as well.
And some older Mooneys have infinite flap settings depending on how much you pump them up...

The reality is that there are no regulations on how many flap settings an airplane must have and on an airliner that may also have things like speed breaks or slats as well, flap settings may vary by design or simply by engineering choice.

Flaps are used for improved short field take off as well as to make a steeper approach at a slower airspeed. If Airbus can achieve desired performance with 4 settings there is no need to complicate matters and add to pilots work load.