The size is exactly what matters. I think we can all agree that filling up a 5,000 gallon water tank with tap water from a vacation home isn't acceptable use.

So the only question is at what point becomes the use too much. A single car might seem harmless but what if it's a group of 4 all arriving with their own car, charging it at the home.

Clarifying what's acceptable and what isn't, is the right decision.