Yes, "cost of running a ZEV is negligible" right now, but only because they are getting a free ride for the use of the road system. A major component of gasoline/diesel prices is a gas tax designed to pay for highway construction and maintenance. I can see the day in the not-too-distant future when governments are going to have to start charging EV owners for the use of the roads - probably an annual licence fee that would be equivalent to what a car owner currently pays in gas taxes at the pump.
All batteries lose their efficiency as they age over multiple charging cycles. EV batteries are no different. The cost of replacing the battery is not insignificant.
On my car, engine maintenance is minimal. The larger expenses are in things like suspension, tires and brakes. This will be the same whether the motive force is derived from fossil fuel or electricity.
Finally, I happen to live in a hot, humid climate near the ocean. The climate is deadly on electrical components. Just deadly!