Majority of aeroplanes are white. Sure, some have stripes, decorations, and names in different colours, but the base colour behind those add-ons is almost always white. There is a real reason for it.
The colour white is a terrific reflector of sunlight, and reflects almost all the light that falls on it, unlike other colours, which absorb some of the light.
If an aeroplane is painted in a colour other than white, it will absorb sunlight and heat up the body of the aeroplane. White reflects that sunlight and avoids the gradual build-up of heat on the plane. This is a good thing, not only when the aeroplane is in flight, but also when it’s parked on the runway.
In fact, some planes actually need to have a coating of white paint in order to guarantee a structurally sound flying machine.
Aeroplanes are regularly inspected for cracks, dents, and any other form of surface damage. Nothing works better than white when it comes to spotting a crack on the surface, as the crack is almost always darker than white.
Additionally, white also accentuates corrosion marks and oil leak spots (as they leave dark-coloured trail). Plus, a white plane is easier to spot (visually) in the event of a crash or any other mishap, especially at night, or in a massive body of water.
Painting a regular Airbus is expensive and the end goal of an airline company is to minimise the cost as much as possible.
When flying at high altitudes, completely exposed to various atmospheric conditions, coloured aeroplanes tend to fade, but a white-colored airplane doesn’t appear significantly different.
Finally, if there’s no problem with the existing white colour, then why bother fixing it at all? The white colour does have its benefits – both scientific and economical.
Though some airline companies do have multi-coloured aeroplanes, white goes with anything.