Seems like the former would have some development costs but ultimately be cheaper to manage
Also, you're reducing demand on the grid by having them at people's homes, not just reducing the demand on the power plants. If the batteries were centralized you'd still need to move that massive amount of power over distribution and transmission lines, which is actually just as big a problem as needing to spin up a peaker plant. In many areas the bottleneck is transmission not generation
I guess Vermont’s relatively low population density makes that more likely; with lower population density each service station will either service fewer homes or require more cabling towards those homes. Either way, more cabling is needed per house. Upgrading that to handle the load of charging a car can be costly.