> This is a bit like saying everyone who walks/bikes to work stops paying their fair share of gas taxes that maintain the roads their food arrives on.

I haven't seen people argue this point for people who don't own a car, but my state does have a special levy on electric and high efficiency vehicles to make up for lost gas tax revenues: https://www.dmv.virginia.gov/vehicles/#highwayuse_fee.asp

They actually do. Gas taxes pay about 60% of the costs to maintain the road infrastructure and given that the damage caused to roads increases as the square of the vehicle's weight, walking/biking causes minimal wear and is offset by the 40% of road costs that come from general taxes.

In this hypothetical, they are still using the Grid to power their homes at night

You added that part.