in cali the power company says "you can use this cost structure or that cost structure, your choice!" - so it's this vile little game where if you choose incorrectly they scalp you, and it takes a bit of arithmetic to compute expected values, power usage at various times of day, etc - something the average joe may not be able to estimate easily. in an ideal world, they would automatically pick the lower of the two.

to a degree I have seen AWS plans work this way, where you choose from options A/B/C and buyer beware if you end up getting scalped.