Reduce heat well
The main reason why the plane is white or colored is to reduce the heat from the sun and shine off the sun and keep the plane from being too hot. For example, if you wear a white shirt, it will not be as hot as a black shirt or a lot of color.
Easy to check
The plane needs regular checks to ensure the safety of flights. And if scratches or broken parts of the body of the aircraft are white, it can be found more easily and faster than other colors.
Not easy to color
In fact, a plane costs a lot of money on spraying, so if it has been able to fly through the sun for some time, it will be very easy to change the color if using a different color than white.
These are the main reasons why airline companies use white and gray on most of their aircraft. But not all companies are also worried about this, because they have to show their company identity on those planes.