Why is the solution to everything "pass a law"? there is an ocean of possible solutions to this problem yet people somehow always jump to "pass more laws" before other options are considered. I find that rather weird.
These are public utilities, so changing their rate structures so significantly could well require legal changes. And if the solution is outside the utility, then it definitely requires legal changes, as then we're in to the realm of business regulation, and American business regulation is generally of the style of "everything is allowed except for these specifically forbidden things that have proven to be bad".
Of course, if you'd like to propose some less intrusive solution I'm sure both we and the people of Central Washington would be all ears.
This is like asking why the solution to bad software is to commit more code.
It's because the way to fix a bad law is to pass another law. Otherwise you're saying we should keep the bad laws we have and work around it some other way.
Sometimes fixing the symptoms actually is better, but it's not surprising when people suggest changing the code.
Also, unless there is a law compelling them to charge miners the same prices, a new law is not needed. The utility can just implement it as a price policy.
Of course, if you'd like to propose some less intrusive solution I'm sure both we and the people of Central Washington would be all ears.