It’s also due to social inertia.
Power companies charge by the kWh because their generators are measured in total output wattage and consumers consume at different wattages at different times.
Sure, it would be easier to measure in total joules consumed per period time but it would also be easier to measure with world standard metric units. The pain of changing is harder than staying the same, so muh freedum units.
Am manager, hate should.
Should presumes an ideal set of conditions with perfect context.
Could is a much better term as it implicitly accepts real world conditions and a lack of total context by couching the affirmation as contingent upon only the discussion (and prior references) at hand.