[unpopular42]

See the OP. They are not charged the amount used. They are charged some weird function of amount used, the rate it was used at, and their home size.

[iaw]

They are charged based on their amount used relative to their fair allocation.

If they use more than their fair allocation everyone else on the grid is subsidizing them so they get charged more to prevent a subsidy. If they use less than their fair allocation they subsidize other people so they're charged less to prevent subsidy.

The electric grid and the electricity that flows over it is a public utility not a commodity.

Edit: Is unpopular42 a throwaway account that you upvote with your main?