Just simply not true!
Actually @NemesisUK is right historically. Driver seats were outside the car cabin, exposed to the elements (mimicking horse drawn carriages). Hence, leather was used for durability, not comfort, while interiors were not leather, for comfort, not durability. Leather was seen as a suitable seating surface for the driver/commoner, not the occupants. It's only later in the 20th century that leather gained the air of luxury.