While the daytime rates are less expensive than the evening peak rates, both are very expensive compared to just about anywhere else.
Workers might start demanding WFH or that their leisure hours be during the day and we can't have that.
I'm not sure "throw out your major appliances that run on electricity and don't even look at plug-in EVs" is the direction we want to go when being able to cheaply meet evening demand at the grid level with renewables is the eventual goal.
Disclaimer: I work for Octopus Energy Group.
The last thing a politician wants to do is lose an election, and losing an election is usually what happens when you suggest that the electorate bear the consequences of their behavior. As a result, we usually drive straight off a cliff, have a war or societal collapse, and then whoever survives it can go build a new system out of the rubble.