Or it could be symbolic of the fact that the situation is more complicated than "stealing is taking what is not yours without getting permission first", because I can think of cases where that is not true. I think it's more about expectations (which can vary with time, culture, experience, etc).
Don't get me wrong; I agree that people should ask first. But what if you drink out of a water fountain - is that stealing water? You didn't ask, it's not your water. But most would not consider it stealing, because the fountain is obviously placed there to make it so people can take a low-cost commodity. I think the determination of whether or not taking something is stealing depends on something other than asking permission.
What about water from an outdoor hose bib, rather than a water fountain? What about an electrical outlet, which is placed to allow electricity use? What if somebody was dry-washing their car and plugged in a radio - is that stealing? I would say those are stealing if you walk on to private property and use them when the homeowner doesn't expect it. But, I think those are all OK for renters of a property to take without asking - because the property owner should expect that. Same action, different expectations.
Charging an EV does cost more than charging a radio, but then we're down to does-stealing-depend-on-the-quantity, which I don't think is a valid frame. I think the best way to look at it is: does the owner of the property EXPECT it to be taken and think it's not a big deal. Water from a water fountain should be fine in every case. Water from a bib or electricity for a radio from an outlet is not fine for a passer-by going on to private property, but is OK for guests and renters of the property.
A renter plugging in a radio should be fine, and charging an EV is just a quantitative extension of the radio. However, the property owner probably thinks EVs cost a lot more to charge than they do, and it's new and not something they expect. Given that I think it's all about the expectations, I would agree you should ask first. At least for now - over time, they may come to expect it.