Why are petrol caps on the driver’s side in some cars and on the passenger’s side in others?

One of the most frustrating experiences of driving a hire car is to pull up at a fuel pump as you would when driving your own car, only to discover that the fuel tank is located on the other side. Car manufacturers could eliminate this difficulty simply by putting petrol caps always on the same side of the car. Why is it like this?

In countries in which motorists drive on the right side of the road, such as the U.S., it is easier to turn right than to turn left across oncoming traffic. A majority of drivers will thus buy fuel at stations they can enter by turning right.

During busy times, all spots on the right sides of pumps would be filled even while most spots on the left sides of pumps remained empty.Suppose fuel tanks were always on the driver's side of the car. Drivers would then have to park on the right side of an open pump in order to fill their tanks.

Putting petrol caps on different sides of different cars means that some cars can access pumps from the left. And this makes it less likely that drivers will have to queue for fuel.