The power utilities don't do that to save the environment. They do it to incentives the EV owners to shift some of the power demand to a time of day that's easier for the power utilities to provide, which is at night.
I have little control of the timing of when my HVAC has to run (whenever I need the house cooler or warmer), when my stove and over run (when I'm hungry), or when my water heater runs (when I use up hot water). But charging an EV can be done at any time from the time you get home that afternoon until the time you leave the next morning (as long as you come home with enough charge to make it to the nearest fast charger in case you all of a sudden have an emergency trip to drive, or have a gas car as a backup). The power utilities have long wanted to shift some of the demand to night when most everything else is off. EV's are a new major demand on the grid, but at least most of the time for local driving it can be done any time of the day that's easier for the utilities.
There's no "shifting" going on. This is just an additional power usage to their normal usage that has already existed.