This has been/is implemented in various parts of the US, but deregulation can go bothways and consumers aren't always happy. When a winter cold snap hits the northeast and energy demand goes up, the market responds as expected. Of course a rational response would be to also consider the savings during other parts of the year, but large seasonal fluctuations in the utility bill does not agree with many consumer's psychology and budgeting habits.
https://www.virginiamercury.com/2020/03/17/va-to-try-limited...