Even without a fiscal incentive, charging at night uses cleaner base load power, places less stress on the grid, and is generally a good thing to do.
Theoretically, charging during peak usage times drives up transmission charges and requires the local distribution utility to upgrade/expand their network. Both result in higher charges that get passed through to their customers in the form of higher rates.
I’m in Houston, no chance you’d overload the grid in the energy capital but I see what you’re saying.