Two residences consume the same monthly energy volume in kWh.
One has a traditional 6 kW instantaneous resistance shower. The other has a 1.5 kW "tank" type water heater that accumulates hot water.
Although both residences consume the same monthly amount of energy, the cost of the electricity sector's value chain is very different, since investments are related to the power demand of each.
The utility company needs to provide 6 kW for one residence and 1.5 kW for the other with respect to water heating.
But the current tariff system does not "recognize" these differences and thus charges the same bill for both residences. And, of course, this inconsistency is "shared" by everyone, without ceremony!