Generally manufacturers sell one vehicle in various markets. These have different tax and emissions regulations, different climates with extremes of heat, cold, altitudes and humidity. They may also have different fuel quantities.
These factors all have to be taken into consideration and can mean substantial compromises in the vehicles set up.
Sales and marketing may also have an effect on the way engines are mapped.
If you look at manufacturer engine specs, the torque graph will rise then flatten out on a straight line and then drop off.
This obviously isn’t how an engine performs optimally, it’s because sales and marketing want to have better torque figures than the competition, and about local market taxation laws.